Merge happy-* library packages into a single happy library component (#292)

[sgraf812]

See #292. Fixes #292.

I'm delighted that git is able to map the renamings, which should make this PR easy to review.

[Ericson2314]

I really do not like this. If the modular boundaries are not enforced, everything will bleed back together. Humans cannot be trusted to manually enforce boundaries during code review, the computer must help.

Does multi-repl not solve all the annoyances of having multiple libraries?

[int-index]

This is a good change because it removes lots of administrative overhead. @Ericson2314's concern is valid, but given the lack of resources to maintain happy I find it justified to prioritize ease of maintenance, release management, etc, over enforcing module boundaries.

@Bodigrim's suggestion in #288 (comment) could be a viable alternative, too. Either way, we need to get rid of those separate .cabal files.

[sgraf812]

Closed in favor of #297.