By adding some PRAY_* macros that encapsulate both the check and the returning of a null reference (UB).
Plus transient avoidance of the flood of warnings emitted by Clang when checking 'this' for NULL.
Plus explanation about the do-while(0) loop in some error macros.
That year should bring the long-awaited OpenGL ES 3.0 compatible renderer
with state-of-the-art rendering techniques tuned to work as low as middle
end handheld devices - without compromising with the possibilities given
for higher end desktop games of course. Great times ahead for the Godot
community and the gamers that will play our games!
(cherry picked from commit c7bc44d5ad)
