Formatting
All Delete operations for stores now return the number of items (of any kind) deleted.
Polish Retcon.Notifications module

Use <> rather than Text operations to concatenate messages together.
Remove dead code.
Updated tests for new delete behaviours
Tidied up Diff module, defined export list to lock down what other modules see
More cleaning up
Tidied up Retcon.Document, added export list
Merge pull request #60 from anchor/wip-returndeletions

Store delete operations return number of items affected
Lensify and sanify StoreMemory
Merge pull request #62 from anchor/wip-difftidy

Improve formatting in Retcon.Diff module
Merge pull request #59 from anchor/wip-polish-notifications

Polish Retcon.Notifications module
Merge pull request #63 from anchor/wip-documenttidy

Polish formatting in Retcon.Document module
Merge remote-tracking branch 'origin/master' into wip-cleanup-memory-store

Conflicts:
	lib/Retcon/Store/Memory.hs
Normalize formatting
Merge pull request #64 from anchor/wip-cleanup-memory-store

Partial cleanup and lensification of Retcon.Store.Memory
Resolve TODOs and formatting of Handler module

Resolve the TODO comments regarding logging output in the Handler
module and, at the same time, the code formatting, comments and
organisation.