Rename mddtypes.h to handle.h
Code cleanup.
Update includes.
Reorganize types.

Made 'Handle' a separate module from the other types.  Moved other types into
forest.h.
Merge branch 'work'

Conflicts:
	src/binaryoperation.h
	src/cache.h
	src/cachenode.h
	src/forest.h
	src/unaryoperation.h
	src/uniquetable.h