Allow to enforce default player using a config variable.

It can be used on Android until screen keyboard will be done.

src/config/user_config.hpp

@@ -592,6 +592,8 @@ namespace UserConfigParams
     PARAM_PREFIX bool m_no_start_screen   PARAM_DEFAULT( false );
 
     PARAM_PREFIX bool m_race_now          PARAM_DEFAULT( false );
+    
+    PARAM_PREFIX bool m_enforce_current_player PARAM_DEFAULT( false );
 
     /** True to test funky ambient/diffuse/specularity in RGB &
      *  all anisotropic */

src/main.cpp

@@ -1679,6 +1679,11 @@ int main(int argc, char *argv[] )
         }
         else if (!UserConfigParams::m_no_start_screen)
         {
+            if (UserConfigParams::m_enforce_current_player)
+            {
+                PlayerManager::get()->enforceCurrentPlayer();
+            }
+
             // If there is a current player, it was saved in the config file,
             // so we immediately start the main menu (unless it was requested
             // to always show the login screen). Otherwise show the login