Offer post-crash safe settings on a per-mod basis

Offer to restore settings when loading a mod that crashed, not the first
mod that gets loaded after a crash. Before the first mod loaded (usually
baseq3) would get the option even if missionpack or some other mod crashed.

- Make pid files separate for each fs_game.
- Remove/write pid every time switching fs_game.
- Create path before writing pid file otherwise it fails on first run.
- Show mod description.txt or fs_game instead of engine name in abnormal
  exit message.
- Check com_fullyInitialized in Com_Error before removing PID,
  otherwise "ioquake3 --version" segfaults when accessing fs_gamevar->string
  (plus not fully initialized isn't really a normal shutdown).

code/qcommon/common.c

@@ -2776,17 +2776,7 @@ void Com_Init( char *commandLine ) {
 
 	Sys_Init();
 
-	if( Sys_WritePIDFile( ) ) {
-#ifndef DEDICATED
-		const char *message = "The last time " CLIENT_WINDOW_TITLE " ran, "
-			"it didn't exit properly. This may be due to inappropriate video "
-			"settings. Would you like to start with \"safe\" video settings?";
-
-		if( Sys_Dialog( DT_YES_NO, message, "Abnormal Exit" ) == DR_YES ) {
-			Cvar_Set( "com_abnormalExit", "1" );
-		}
-#endif
-	}
+	Sys_InitPIDFile( FS_GetCurrentGameDir() );
 
 	// Pick a random port value
 	Com_RandomBytes( (byte*)&qport, sizeof(int) );