Use dedicated hash table for new material names.
Updates a lot of dependent code:
- surface patches now target materials, not textures:
`s/_xvk_textures/_xvk_material`
- patching now affects only materials, not texture ids. All logic that
depends on texture ids now operate on original textures.
- brush normal smoothing now ignores patched surface materials when
deciding whether two surfaces can be smoothed.
The rationale is that patching should only affect newer PBR/RT code paths.
Ivan Avdeev