thick curve bug

[BruceSherwood]

There is a problem with the thick version of the curve object:

y = 1 # if y is 0 and radius is nonzero, nothing is displayed
c = curve(pos=[(0,y,0)], radius=0.2)
c.append(pos=(0,y,0))
c.append(pos=(1,y,0))

Evidently the thick version of the curve object needs to discard duplicate initial points.

[BruceSherwood]

Fixed by commit of 2014 June 28 to eliminate initial duplicate points of a curve (curve.cpp).