Option to automatically delete generated `.sw.vtx` files?

[SirYodaJedi]

The "software" VTX files are only used by DirectX 7 and lower, which have been unsupported since Source 2007. This causes them to just waste space, so I usually use a batch script to delete them. It'd be nice if Crowbar had an option to do that automatically.

I would just use -fastbuild, but this also omits the dx80 versions, which are necessary for stock VRAD to compile static prop lighting in pre-L4D games.

[StainterSB]

I never really use dx8 or below i only use dx9 for all of my games but studiomdl does it