Added the capture-counter and changed the CTF scoreboard to display the caps.

Added the capture-counter and changed the CTF scoreboard to display the caps.
Gameplay changes:
cvar g_ctf_win_mode:
2 to play as usual, with just a fraglimit
1 use the teamfrags if the team-captures are equal
0 use overtime
cvar capturelimit - does it need explanation?
g_ctf_flagscore_kill - frags to get when killing the carrier (default 6)
g_ctf_flagpenalty_drop - frags to lose when dropping the flag (default 0)

git-svn-id: svn://svn.icculus.org/nexuiz/trunk@3780 f962a42d-fe04-0410-a3ab-8c8b0445ebaa