Sanitise stopping of player-related particle systems.
G/Admin: Register user-defined admin commands
Stop jetpack and muzzle particle systems when client entity leaves PVS.
Fix line breaks in rcon output.
Use Str::cisspace in a few more places
Fix tab complete not adding a space.

Thanks Amanieu.
Changelog update.
debian: Add a MIME file so that unv:// is handled automatically.