Three improvements involving image caching:

1) prevent the textureQuad map from containing references to cards when we're returning a temp (card backdrop) image in the threaded version.
2) we had two copies of the pspicon image in the cache (ie the regular & managed).  Changed the reference in the DeckMenu code to use the managed instance.
3) Fixed a problem with a default constructor param that would set RESOURCE_LOCKED on certain images.  I noticed that the 'NEW' image was locking itself in the cache because no resource modes was being passed in, so the default constructor param was setting it to locked.  This seems like a bad idea - if you're not explicitly locking a resource in the call, that shouldn't be the default behaviour.

Also added an assert safeguard to catch the possibility of 'overlocking' an image resource, as this probably means the image fetching routine is being abused somehow.

projects/mtg/src/WResourceManager.cpp

@@ -23,9 +23,6 @@ namespace
     const std::string kExtension_gbk(".gbk");
     const std::string kExtension_font(".font");
 
-    const std::string kGenericCard("back.jpg");
-    const std::string kGenericThumbCard("back_thumb.jpg");
-
     // mutex meant for the cache map
     boost::mutex sCacheMutex;
     // mutex meant to protect against unthread-safe calls into JFileSystem, etc.