Resolve packages using dataDir (closes #216, closes #212, closes #213, closes #220).
Ignore EThingAll qualified exports (for fay-base), note that qualified imports are still not supported.
Rename Fay$$div to Fay$$divi, fixes name clash with Prelude.div in newest fay-base.
Revert "Disable caching of imports (fixes #215), and make sure stateImported is never cleared"

This reverts commit f4083aaf17a0ff821bcbc00cdddcdf268565b568.

Conflicts:
	src/Language/Fay/Compiler.hs
	src/Language/Fay/Types.hs
Merge branch 'faylang' into with-fay-base