Fixes: Alert plugin fallback functionality, Commandline arguments fix.

Fix alert plugin bug if statplayercount isnt available
- If statplayercount isn't available, reverts to the old functionality
of having alerts appear at the specified interval, if it IS, then it
checks if the current player count is more than or equal to the minimum
player count.
Split server command line arguments
- mark2.service.process.server-args=nogui;--world
worldname;--max-players 64