WIP: Add BGRA_SRGB and add tweak to use an RGBA surface as BGRA when requested
This tweak replaces the bgra tweaks from !207 (closed) because it is more stable, i.e. with !207 (closed) Portal starts flickers when the tweak is enabled, with this patch this is fixed and it also helps with The Raven Remastered, HL2, and L4D2.
Closes #94 (closed) Closes #91 (closed)
WIP because the series is on top of !173 (merged) (required to get proper rendering with the Valve games)