major rework of plot_box

add plot_arrow
generalize color handling
control whether curve is closed for circle/ellipse
add cylinder primitive
fix dims for 3D case

Author: petercorke

spatialmath/base/__init__.py

@@ -316,6 +316,7 @@
     "sphere",
     "ellipsoid",
     "plot_box",
+    "plot_arrow",
     "plot_circle",
     "plot_ellipse",
     "plot_homline",