Fix texture issues

[stingray300k]

Right now, exported standard Q3 maps converted via q3map2 open fine in NetRadiant, but moving a wall makes it crash because it can't handle the texture transform. So something is wrong. Could be just that standard Q3 textures aren't fully supported by io_export_qmap => try using qbsp to convert from Valve220 to Brush Primitves.

[stingray300k]

qbsp from ericw-tools automatically repairs the texture projection from both Valve220 and Quake Standard maps when converting to BP. The resulting maps no longer make NetRadiant crash when moving brushes around, which is great. So, for the time being, there should be another path in the addon preferences pointing to an ericw-tools installation, which can be used to post-process the map automatically.

After that, the next step would be whether actual texture projections (the ones that made NetRadiant crash were io_export_qmap's "dummy" projection for meshes without any UV maps defined!) work.