Blender Git Loki

Cleanup: GPUState: Remove GPU_state_init()

GPUState: Use GPU_viewport to set viewport state in GPU_framebuffer

also fix a small issue in GPU_texture_clear.

GPUState: Port default state to StateManager constructor

Cleanup: DRW: Use GPUState instead of raw opengl calls

Should not break anything! Huh!

GPUState: Only apply state before drawing

Cleanup: GPUState: Remove stack from the state manager and rename it

GPUState: Remove gpuPushAttr/gpuPopAttr

And use manual save/restore mechanism.

The stack method is not used so much to be considered useful.

GPUState: Make use of GPUStateStack class

This isolate most GL calls to the GL backend. Still a few remains.

Cleanup: GPUState: remove double GPU_blend calls

GPUState: GPU_blend final API renaming

We now use GPU_blend for enabling / disabling blending and explicitly
set the blend equation.

Cleanup: GPUState: remove use of GPU_blend_set_func

Cleanup: GPUState: Replace blend func separate by enum

Cleanup: GPU: Move towards an explicit Blend state

This make use of the GLStateStack functions for:
- `GPU_blend()`
- `GPU_blend_set_func()`
- `GPU_blend_set_func_separate()`

The goal is to unify them using an explicit state setting.
This will remove the need to use obscure blend functions

GPUState: Add GL backend and state tracking but do not use it

This is just the backend work. It is not plugged in yet because it
needs more external cleanup/refactor.

Cleanup: GPU: Remove uneeded depth precision getter.

We always use 24bit framebuffers nowadays.

Cleanup: GPUState: remove float variant of GPU_scissor_get

GPUShader: Add debug labels

This allow better debugging inside renderdoc.

GPUShader: Add back vertformat_from_shader()

GPUShader: Improve auto name

Use macro to get calling function name. Helps debugging shaders.

GPUShader: Rewrite error printing

Now error printing only display the line related to the error.
We also put char marker if present.

Example:
```
-- Shader Compilation Errors : MAMaterial --

10414 | node_fresnel(, facingnormal, viewposition, tmp34);
| ^
| error: syntax error, unexpected ',', expecting ')'

----------------------------------
```