Fix -Wmissing-home-modules warnings

[RyanGlScott]

Fixes #434.

[treeowl]

I tried to fix this thing up, but goofed something up. Can you please rebase?

[RyanGlScott]

Done.

[treeowl]

Why do so many modules need to be listed so many places? Is there some way to restructure things to avoid this?

[RyanGlScott]

Unfortunately, this is an annoying problem that many core libraries like containers face. What one would like to do is list containers as a library dependency in each test suite and benchmark, which would obviate the need to duplicate all of these other-modules. But containers' test suites and benchmarks depend on libraries which themselves depend on containers. For apparently technical reasons, this prevents us from listing containers as a library dependency there, because Cabal would be confused as to whether to link against the version of containers used to build the dependencies, or the version of containers you're building from source. (See haskell/cabal#4087 for an attempt to fix this issue in Cabal.)

Thus, we can't list containers as a library dependency, which means that we pretty much have to duplicate the other-modules for now. (A possible workaround for this in the future would be to list every thing in other-modules in a Cabal common stanza.)

[treeowl]

Thanks.