[SP] Fix invalid "dll" being loaded on non windows systems with regards to jk2 vs ja.

Still had leftover com_jk2 check instead of preprocessor define.
[SP] Install the JO renderer on OSX with JO not with JA.
[SP] Disable some JA hardcoded real cvars in UI if running JK2 mode.
[MP] Fixed an issue introduced during server side demo addition which introduced player colors and extended ascii being stripped from names.

This didn't show up in-game but it would have showed up in external tools receiving the player list /serverstatus, ingame browser player list, or rcon status etc.
[MP] Use correct origin/angles so that moving brushes work properly (ie moving water)
Enabled multicore compilation on MSVC