Removed Murmur hash references and added elemental attribute

1. Removed references to the murmur hash from stdlib_64_bit_hash_codes.fypp
2. Described all fibonacci and universal_mult_hash procedures as elemental
2. Described fnv_1, FNV_1a, nmhash32, nmhash32x, water_hash, pengy_hash
   operating on character strings as elemental.

[ticket: X]

Author: wclodius2

src/stdlib_32_bit_fnv_hashes.fypp

@@ -61,7 +61,7 @@ contains
 #:endfor
 
 
-    pure module function character_fnv_1( key ) result(hash_code)
+    elemental module function character_fnv_1( key ) result(hash_code)
 ! A default character key wrapper for the FNV-1 algorithm.
         character(*), intent(in)      :: key
         integer(int_hash)             :: hash_code
@@ -112,7 +112,7 @@ contains
 
 #:endfor
 
-    pure module function character_fnv_1a( key ) result(hash_code)
+    elemental module function character_fnv_1a( key ) result(hash_code)
 ! A default character key wrapper for the FNV-1 algorithm.
         character(*), intent(in)      :: key
         integer(int_hash)             :: hash_code

src/stdlib_32_bit_hash_codes.fypp

@@ -81,7 +81,7 @@ module stdlib_32_bit_hash_codes
 
         #:endfor
 
-        pure module function character_fnv_1( key ) result(hash_code)
+        elemental module function character_fnv_1( key ) result(hash_code)
 !! FNV_1 hash function for default character string keys
             character(*), intent(in)      :: key
             integer(int_hash)             :: hash_code
@@ -100,7 +100,7 @@ module stdlib_32_bit_hash_codes
 
         #:endfor
 
-        pure module function character_fnv_1a( key ) result(hash_value)
+        elemental module function character_fnv_1a( key ) result(hash_value)
 !! FNV_1A hash function for default character string keys
             character(*), intent(in)      :: key
             integer(int_hash)             :: hash_value
@@ -122,7 +122,7 @@ module stdlib_32_bit_hash_codes
 
         #:endfor
 
-        pure module function character_nmhash32( key, seed ) &
+        elemental module function character_nmhash32( key, seed ) &
             result(hash_value)
 !! NMHASH32 hash function for default character string keys
             character(*), intent(in)      :: key
@@ -146,7 +146,7 @@ module stdlib_32_bit_hash_codes
 
         #:endfor
 
-        pure module function character_nmhash32x( key, seed ) &
+        elemental module function character_nmhash32x( key, seed ) &
             result(hash_value)
 !! NMHASH32 hash function for default character string keys
             character(*), intent(in)      :: key
@@ -169,7 +169,7 @@ module stdlib_32_bit_hash_codes
           end function ${k1}$_water_hash
         #:endfor
 
-        pure module function character_water_hash( key, seed ) &
+        elemental module function character_water_hash( key, seed ) &
             result(hash_code)
 !! WATER hash function for default character string keys
             character(*), intent(in)   :: key
@@ -205,7 +205,7 @@ module stdlib_32_bit_hash_codes
 
 contains
 
-    pure function fibonacci_hash( key, nbits ) result( sample )
+    elemental function fibonacci_hash( key, nbits ) result( sample )
 !! Maps the 32 bit integer KEY to an unsigned integer value with only NBITS
 !! bits where NBITS is less than 32
         integer(int32), intent(in) :: key
@@ -216,7 +216,7 @@ contains
 
     end function fibonacci_hash
 
-    pure function universal_mult_hash( key, seed, nbits ) result( sample )
+    elemental function universal_mult_hash( key, seed, nbits ) result( sample )
 !! Uses the "random" odd 32 bit integer SEED to map the 32 bit integer KEY to
 !! an unsigned integer value with only NBITS bits where NBITS is less than 32
         integer(int32), intent(in) :: key

src/stdlib_32_bit_nmhashes.fypp

@@ -724,7 +724,7 @@ contains
 
 #:endfor
 
-    pure module function character_nmhash32( key, seed ) result(hash_code)
+    elemental module function character_nmhash32( key, seed ) result(hash_code)
 !! NMHASH32 hash function for default character keys
         character(*), intent(in)   :: key
         integer(int32), intent(in) :: seed
@@ -749,7 +749,7 @@ contains
 
 #:endfor
 
-    pure module function character_nmhash32x( key, seed ) result(hash_code)
+    elemental module function character_nmhash32x( key, seed ) result(hash_code)
 !! NMHASH32X hash function for default character keys
         character(*), intent(in)   :: key
         integer(int32), intent(in) :: seed

src/stdlib_32_bit_water_hashes.fypp

@@ -250,7 +250,8 @@ contains
 
 #:endfor
 
-    pure module function character_water_hash( key, seed ) result(hash_code)
+    elemental module function character_water_hash( key, seed ) &
+        result(hash_code)
         character(*), intent(in)   :: key
         integer(int64), intent(in) :: seed
         integer(int_hash)          :: hash_code

src/stdlib_64_bit_fnv_hashes.fypp

@@ -62,7 +62,7 @@ contains
 
 #:endfor
 
-    pure module function character_fnv_1( key ) result(hash_code)
+    elemental module function character_fnv_1( key ) result(hash_code)
         character(*), intent(in)      :: key
         integer(int_hash)             :: hash_code
 
@@ -112,7 +112,7 @@ contains
 
 #:endfor
 
-    pure module function character_fnv_1a( key ) result(hash_code)
+    elemental module function character_fnv_1a( key ) result(hash_code)
         character(*), intent(in)      :: key
         integer(int_hash)             :: hash_code
 

src/stdlib_64_bit_hash_codes.fypp

@@ -99,7 +99,7 @@ module stdlib_64_bit_hash_codes
           end function ${k1}$_fnv_1
         #:endfor
 
-        pure module function character_fnv_1( key ) result(hash_code)
+        elemental module function character_fnv_1( key ) result(hash_code)
 !! FNV_1 hash function for character strings
             character(*), intent(in)   :: key
             integer(int_hash)             :: hash_code
@@ -118,39 +118,14 @@ module stdlib_64_bit_hash_codes
           end function ${k1}$_fnv_1a
         #:endfor
 
-        pure module function character_fnv_1a( key ) result(hash_code)
+        elemental module function character_fnv_1a( key ) result(hash_code)
 !! FNV_1A hash function for character strings
             character(*), intent(in)   :: key
              integer(int_hash)         :: hash_code
         end function character_fnv_1a
 
     end interface fnv_1a_hash
 
-
-    interface murmur2_hash
-!!  MURMUR2_HASHES interfaces
-
-        #:for k1 in INT_KINDS
-          pure module function ${k1}$_murmur2_hash( key, seed ) &
-              result(hash_code)
-!! MURMUR2 hash function for rank 1 arrays of kind ${k1}$
-              integer(${k1}$), intent(in) :: key(0:)
-              integer(int_hash), intent(in)  :: seed
-              integer(int_hash) :: hash_code
-          end function ${k1}$_murmur2_hash
-        #:endfor
-
-        pure module function character_murmur2_hash( key, seed ) &
-            result(hash_code)
-!! MURMUR2 hash function for character strings
-            character(*), intent(in)    :: key
-            integer(int_hash), intent(in)  :: seed
-            integer(int_hash) :: hash_code
-        end function character_murmur2_hash
-
-    end interface murmur2_hash
-
-
     interface spooky_hash
 !! SPOOKY_HASH interfaces
 
@@ -234,7 +209,7 @@ interface
     end function ${k1}$_pengy_hash
         #:endfor
 
-        pure module function character_pengy_hash( key, seed ) &
+        elemental module function character_pengy_hash( key, seed ) &
             result(hash_code)
 !! MIR HASH STRICT function for character strings
             character(*), intent(in)      :: key
@@ -255,7 +230,7 @@ interface
 
 contains
 
-    pure function fibonacci_hash( key, nbits ) result( sample )
+    elemental function fibonacci_hash( key, nbits ) result( sample )
 !! Maps the 64 bit integer KEY to an unsigned integer value with only NBITS
 !! bits where NBITS is less than 64
         integer(int64), intent(in) :: key
@@ -266,7 +241,7 @@ contains
 
     end function fibonacci_hash
 
-    pure function universal_mult_hash( key, seed, nbits ) result( sample )
+    elemental function universal_mult_hash( key, seed, nbits ) result( sample )
 !! Uses the "random" odd 64 bit integer SEED to map the 64 bit integer KEY to
 !! an unsigned integer value with only NBITS bits where NBITS is less than 64.
         integer(int64), intent(in) :: key

src/stdlib_64_bit_pengy_hashes.fypp

@@ -118,7 +118,8 @@ contains
 
 #:endfor
 
-    pure module function character_pengy_hash( key, seed ) result(hash_code)
+    elemental module function character_pengy_hash( key, seed ) &
+        result(hash_code)
 !! PENGY_HASH hash function for default character keys
         character(*), intent(in)   :: key
         integer(int32), intent(in) :: seed