Apply clang format as proposed in T53211.
For details on usage and instructions for migrating branches
without conflicts, see:
https://wiki.blender.org/wiki/Tools/ClangFormat
Updated shader names and code that uses them.
All of these shaders produce round points that are anti-aliased and blended against the background.
These were initially named SMOOTH because they replace glEnable(GL_POINT_SMOOTH). But SMOOTH in shader-land refers to vertex attribute interpolation (like glShadeModel(GL_SMOOTH)).
Using SMOOTH to mean two things is confusing, so we now use AA to mean "the point is anti-aliased".
