Made "gametype" in infoResponse a string

Server use to just give the gametype number, which is only useful if UI is modified to support that mod.
Now q3_ui/ui server browser displays correct gametype for servers running different mods.

Added two new cvars sv_gametypeName (i.e. Free for All) and sv_gametypeNetName (i.e. FFA). sv_gametypeNetName is used for "gametype" in infoResponse.
Make cgame use gametype name from server

Use new sv_gametypeName cvar/serverinfo to allows server-side mods to have different gametype names. Gets rid of some duplicate copies of gametype names too.