COMMON: Create a sampler state for point sampling w/ wrapping
OBJ_LOADER_DEMO: Implement alpha clipping
OBJ_LOADER_DEMO: Modify the specular color for the materials with spec maps

The previous color was (0.0f, 0.0f, 0.0f), which didn't allow any specular. I changed it to
(0.5f, 0.5f, 0.5f), based on what "looked right". (1.0f, 1.0f, 1.0f) was too shiny for stone.
OBJ_LOADER_DEMO: Fix a bug in the forward shader specular calculations

Specular power is never compressed in forward shading. Therefore, it doesn't
need to be uncompressed.
OBJ_LOADER_DEMO: Scale the camera sensitivity with the scene scale