vis_point cannot accept user defined colors for each point.

[apple2373]

chainercv/chainercv/visualizations/vis_point.py

Line 9 in 9fe62c8

def vis_point(img, point, visible=None, ax=None):

I think it's nice if it can take instance_colors in a similar manner to vis_box.

[yuyu2172]

Thank you for pointing that out.