SetTeam fix from Martin Doucha.

"Actually, client->ps.clientNum is unsafe. We had a little hunt for this some
time ago in Tremulous last year (it caused kick failures, annoying popup
windows and other nasty bugs). The problem is that a following spectator gets
full copy of client->ps of the followed player including clientNum. If you then
try to use this "shared" clientNum, you might affect someone else than you
wanted.

r1019 changes are safe as long as bots don't spectate players. However, a brief
grep on current code has revealed unsafe client->ps.clientNum usage in
SetTeam(). If a following spectator uses team command when forced balance is
on, it'll count teams incorrectly and send the error message to the followed
player instead. Here's the fix."

  Fixes Bugzilla #2986.

code/game/g_cmds.c

@@ -523,17 +523,17 @@ void SetTeam( gentity_t *ent, char *s ) {
 		if ( g_teamForceBalance.integer  ) {
 			int		counts[TEAM_NUM_TEAMS];
 
-			counts[TEAM_BLUE] = TeamCount( ent->client->ps.clientNum, TEAM_BLUE );
-			counts[TEAM_RED] = TeamCount( ent->client->ps.clientNum, TEAM_RED );
+			counts[TEAM_BLUE] = TeamCount( clientNum, TEAM_BLUE );
+			counts[TEAM_RED] = TeamCount( clientNum, TEAM_RED );
 
 			// We allow a spread of two
 			if ( team == TEAM_RED && counts[TEAM_RED] - counts[TEAM_BLUE] > 1 ) {
-				trap_SendServerCommand( ent->client->ps.clientNum, 
+				trap_SendServerCommand( clientNum, 
 					"cp \"Red team has too many players.\n\"" );
 				return; // ignore the request
 			}
 			if ( team == TEAM_BLUE && counts[TEAM_BLUE] - counts[TEAM_RED] > 1 ) {
-				trap_SendServerCommand( ent->client->ps.clientNum, 
+				trap_SendServerCommand( clientNum, 
 					"cp \"Blue team has too many players.\n\"" );
 				return; // ignore the request
 			}