Merge pull request #46 from anchor/wip-repo-structure

Reorganise into src/ and lib/ directories.
Update Makefile to format and lint lib/
Some documentation and formatting
These are bad to ignore.
Many lint issues fixed
Merge pull request #49 from anchor/wip-lint-and-format

Wip lint and format
Merge remote-tracking branch 'origin/master' into wip-extend-store-api

Conflicts:
	lib/Retcon/Store/Memory.hs
	lib/Retcon/Store/PostgreSQL.hs