(Feature Request) Add support for Vera Visions formats

[pixe1reality]

It would be helpful for developing FTEQW standalone projects (and help make custom maps for the game The Wastes that uses FTEQW) if there was support for VVM models and .mat shader files.

VVM models are IQM models with extended features for in-game usage. IQM models have existing support in AssetLib, but since VVM models have a different file extension it is not recognised. Specifications for the format, in case it differs too much from IQM can be found here: https://github.com/fte-team/fteqw/tree/master/iqm

The Nuclide SDK for FTEQW has a special material file format derived from Quake 3's shaders that exist as separate material files per shader definition. NetRadiant-Custom already supports Quake 3 shaders, but I'm not sure how much more work it would be to recursively find shader files within the texture folder. Specifications for the material commands (in case editor-specific commands have differences) can be found here: https://developer.vera-visions.com/d5/de1/mat_commands.html

[Garux]

I'm not volunteering to support number of formats flavours added by single game. But from description these two things are doable via PR.

Assimp may handle multiple extensions per loader, so basic IQM loader may be reused for your format flavour.

.mat support seems okay, if implemented modularly enough, as in not bloating existing shaders loading.