- Change runtime standalone detection:

* com_standalone now read-only
  * add new cvars com_basegame, com_homepath
  * standalone now automatically detected when com_basegame is set to something different than baseq3 and no id pak pk3s are found
  * This fixes https://bugzilla.icculus.org/show_bug.cgi?id=4699
- Replace a few hardcoded string literals with macros
- Add checks for Team Arena PK3s to FS_CheckPak0()

code/client/cl_main.c

@@ -2106,7 +2106,7 @@ void CL_CheckForResend( void ) {
 	case CA_CONNECTING:
 		// requesting a challenge .. IPv6 users always get in as authorize server supports no ipv6.
 #ifndef STANDALONE
-		if (!Cvar_VariableIntegerValue("com_standalone") && clc.serverAddress.type == NA_IP && !Sys_IsLANAddress( clc.serverAddress ) )
+		if (!com_standalone->integer && clc.serverAddress.type == NA_IP && !Sys_IsLANAddress( clc.serverAddress ) )
 			CL_RequestAuthorization();
 #endif