% Draws a simple arrow in 2D, from p0 to p1.
% p0 = [x0; y0] = position of the tail
% p1 = [x1; y1] = position of the tip
% color = arrow color. Optional: default is black
% --> can be 'r','g','b','c','m','y','w', 'k' or a 1x3 color vector
% hArrow = handle to the patch object representing the arrow