Added code for parsing dungeon pack config files. The settings for our
built-in dungeons are now read from a file instead of being hardcoded.
One or two settings aren't being accessed yet and we still don't search
for other dungeon packs in the custom dungeon folder. That'll come in
another commit.
Made some changes to EventHookContainer.onWorldLoad() to remove
redundant code that encouraged bugs. Unfortunately, a lot of
link-related code needs to be rewritten to get rid of bugs, so that'll
come after dungeon packs are completed.
