Now it is more verbose and the status is checked at the right moment (previously it was fine with Linux, but on Windows it showed errors).

Fixed blending function for OpenGL compositing. Corrected documentation, removed unnecessary functions.

Code refactorization. VBO_CONTAINER is split to [NON]CACHED_MANAGER, GPU_MANAGER and VERTEX_MANAGER.

Added separate layers for pad netnames (now these are divided into multilayer/top/bottom pads).
More appropriate layers are selecting a copper layer in the high contrast mode (now it shows the copper layer itself, vias & multilayer pads and netnames).

1 pixel wide outlines for the Cairo and the OpenGL with shaders backends, but it breaks displaying outline in the shaderless OpenGL backend.