Prevent displaying remote servers on startup of LAN servers browser

After startup of LAN servers browser there appeared sometimes also remote
servers, instead of only LAN servers.
I such case "si.lastpingmillis=servermenumillis" for all remote servers.
So this commit changes a little existing condition, to prevent above
problem.
Drop activated grenade, when player switches to edit mode
Turn off sniper rifle's scope during intermission
Disable listdemos and getdemo in singleplayer
Removed unnecessary restrictions of switching to SPECTATOR team

Note: spectate() function doesn't have such restrictions.