Just some problems with lightmaps. There also seem to be some issues with
seams (t-junctions?) and far clip, but they're quite separate.
There's also a problem with a segfault when loading a second map.
The entire vertex set from every model is put into one list (not yet
uploaded). chains of elements arrays are build for non-instanced models
(instanced models will have their chains built each frame).
Still nothing being rendered: still in the process of building the display
lists, but I'm making good progress. Get this into git before something
goes wrong :)