Remove multisample antialiasing (MSAA)

[no-lex]

Multisample AA has serious performance issues on the engine's renderer, a fact reflected in Tesseract's renderer document:

Since Tesseract relies upon deferred shading, simply using MSAA by itself does not provide adequate performance due to increasing memory bandwidth usage from large multisampled g-buffer textures, though Tesseract does, in fact, implement stand-alone MSAA in spite of deferred shading.

Because it is not a particularly useful AA type due to its lousy performance, MSAA as a feature is rather pointless. SMAA provides essentially indistinguishable performance at a much lower cost.