HEXTERMINATE - Build 18 update

Hello everyone.

This build contains substantial engine changes ahead of a public Linux build and these changes touch many parts of the game. If you find a bug or a crash, please jump on the forum and let me know!

• Added new Codex to the main menu, with descriptions of the various modules and factions.
  
• Added vignette post-processing effect.

• Upgraded post-processing pipeline, which is more performant and allows for improved effects.
  
• Re-wrote the glow effect, addressing various banding artefacts.
  
• Split audio system into Windows and Linux implementations.
  
• Now using cross-platform implementation for identifying the resolution of the current screen.

• Fixed several rendering issues which could result in the game presenting a black screen.
  
• Fixed various stuttering issues by adding a dedicated loading screen between the intro movie and the main menu.
  
• Fixed several memory leaks.