Built-in shaders now use uniforms instead of legacy built-in matrices. So far I only hooked this up for new immediate mode. We use the same matrix naming convention as OpenGL, but without the gl_ prefix, e.g. gl_ModelView becomes ModelView. Right now it can skip the new matrix stack and use the legacy built-in matrices app-side. This will help us transition gradually from glMatrix functions to gpuMatrix functions. Still some work to do in gpuBindMatrices. See TODO comments in gpu_matrix.c for specifics.