finally hacked together a vertex merging algorithm

if vertices get too close, they are merged (but not really...the
"pinched off" faces are simply set to 0, 0, 0 and the deleted vertex is
just moved to -1000, -1000, -1000 because of some bullshit about not
resizing buffers)
Revert "finally hacked together a vertex merging algorithm"

This reverts commit a472c1bc2a3ba01cd26d770271bd7aa386d0823c.
Revert "Revert "finally hacked together a vertex merging algorithm""

This reverts commit e3016e61898ff38fb2038a91fed540ec057f01a4.