[M-dev]Overhead Map Problem--Edges Smearing

[Hentai D. <hen...@ph...>]

The edges of the overhead map aren't getting redrawn properly when the 
map changes. In particular, the solid lines of the map leave a 
single-pixel residue on the edges. An example can be seen at 
<http://www.columbia.edu/~agd12/overhead_map_edges.jpg>. This is from 
the latest A1 Carbon build, using Do Map in OpenGL and Pipe 2D Thru 
OpenGl.
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