WAD Refactor

Refactored some of the code for the wadfile reading. Moved out the
readers into their own separate file, and moved some utilities around to
create wad utilities for more modularity.

src/wad/mod.rs

@@ -1,4 +1,4 @@
 mod header;
-mod wadfile;
+pub mod wadfile;
 
 pub use wadfile::WADFile;