Conflicts:
	src/Haddock/Convert.hs

Conflicts:
	src/Haddock/InterfaceFile.hs

This setup makes more sense since when we add value bindings to the
processed declarations (for type inference), we will have multiple
declarations which should share documentation. Also, we already have
a separate doc map for instances which we can now merge into the
main doc map. Another benefit is that we don't need the DeclInfo
type any longer.

haddock's .cabal file was declaring that it needed alex and happy to
build, but in the GHC source tarballs it doesn't.

- Docs don't get attached to the next top-level with signature by
mistake.

- If there's an export list and the top-level is part of it,
its doc comment shows up in the documentation.