Blender Git Loki

Merge branch 'master' into tmp-widget-opti

# Conflicts:
# source/blender/gpu/shaders/gpu_shader_2D_widget_base_vert.glsl

UI: Widget: Replace geometry by fragment shader drawing

This means all the antiailasing is done inside the fragment shader.

We use a Signed Distance Field to draw the 2D rounded boxes. This ensure
the best quality for AA.

This reduce the averge Batch for widget to 16 verts instead of ~600 and
reduce overshading a lot.

Theme Emboss alpha and tria alpha needs to be changed after this refactor.

UI: Widget: Make emboss offset dependent of line width

UI: Widgets: Reduce constants count in shader

Cleanup: Put GPU_state_init inside gpu_state.c

Also put glDisable(GL_DITHER) in it since we don't even use it (but is
enabled by default).

Also leave GL_MULTISAMPLE on by default since it has no impact on non-MSAA
framebuffers.