Vertex snapping now works with backbuffered selection modes. Previously
backbuffer sampling had no way to check whether or not the indices that
it retrieved were selected or not. To resolve this I added two optional
arguments to sample_backbuf_rect in drawview.c. The first argument tells
the function that some additional testing of the retrieved index values
needs to be done and the second argument is a pointer to a function to
do the testing. findnearestvert() in editmesh_mods.c now makes use of this
and passes sample_backbuf_rect() the appropriate argument when being used
for vertex snapping.
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