- Update to version 2.10
* Refine the 'g_footstep' cvar to match Quake II itself.
* Implement 'g_machinegun_norecoil'. The cvar is cheat protected.
* Fix soldiers never showing their pain skins as long as they're
alive.
* Fix laser guard trying to fire two shots when dying.

- Update to version 2.09
- Fix wrong sound for some items when activated.
- Port the 'aimfix' cvar.
- Port the 'coop_pickup_weapons' and 'coop_elevator_delay' cvars.
- Fix a long standing crash occuring when exploding projectiles
like grenates or rockets generate sound targets and a least one
monster starts moving to one of that targets.
- Add a cvar `g_footsteps` to control the generation of footstep
sound.
- Move several hard coded map fixes to entity files. Add newly
discovered mapfixes to the entity files.
- Fix several subtile gameplay and entity handling bug.