Fix AMP warnings

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Update Git repo URL in `.cabal` file
Add test helper
Fixes #231
Fixes #256

We inject -dynamic-too into flags before we run all our actions in the
GHC monad.
Add new field to DynFlags
Fallback to ./resources when Cabal data is not found

(so that themes are found during development)
Fixes #5
Print missing documentation. Fixes #258.