Added the ability to load linedefs from a wad file. Also added
functions to the linedef type to allow you to check the status of
each bit of the flags value making it very easy to check linedef
properties.
Added the ability to parse the directory and store it in a
Directory struct. This data has utility functions that can be used
to work with the directory to find any lump we could need. This
patch should fix up issue #3.
