Log Message:
Update prboom to version 2.2.3

Changes from v2.2.2 to v2.2.3
- improved mouse handling
- intermission demo sync bug fixed
- framebuffer update fixes (solves flicker on fbcon)
- -forceoldbsp allowed in non-GL version, and saved in demos
- fix player colours in multiplayer demos
- apply workarounds for buggy pwads even during demo playback
- fix numpad 5 key
- allow compilation on systems where SDL is built without joystick support
- fix comp_skymap
- using anisotropic filtering when the OpenGL extension is available
- using paletted textures when the OpenGL extension is available
- added gl_use_paletted_texture option to glboom configuration file
- using shared texture palette when the OpenGL extension is available
- added gl_use_shared_texture_palette option to glboom configuration file