Implement loading of .meg files using the Resource manager

- I extract pixel data from the resource without using QuickDraw
- Both resource-fork and data-fork .meg files work

Related changes:
- The custom graphics textures are now wrapped in a custom class
- bmp images are loaded if a meg is not found

Incidental changes:
- Various TODO notes
- Fix cScenario::spec_strs skipping several strings and potentially fetching out-of-bound entries
- oopsError now uses string streams instead of sprintf

osx/BoE.xcodeproj/xcshareddata/xcschemes/Blades of Exile.xcscheme

@@ -64,7 +64,7 @@
       shouldUseLaunchSchemeArgsEnv = "YES"
       savedToolIdentifier = ""
       useCustomWorkingDirectory = "NO"
-      buildConfiguration = "Release"
+      buildConfiguration = "Debug"
       debugDocumentVersioning = "YES">
       <BuildableProductRunnable>
          <BuildableReference