Allow running indoors

Credit to TheXaman for posting this in the Simple Modifications Pokecommunity thread.

This tutorial will allow the player to run on any map.

Normally, the game checks the map header to see if the player is allowed to run on the map. All we need to do is remove that check.

Edit src/bike.c:

 bool32 IsRunningDisallowed(u8 metatile)
 {
-    if (!gMapHeader.allowRunning || IsRunningDisallowedByMetatile(metatile) == TRUE)
+    if (IsRunningDisallowedByMetatile(metatile) == TRUE)
         return TRUE;
     else
         return FALSE;
 }

And that's it!