Update option parsing to work with latest optparse-applictive.

* Rework option parsing code.
* Add constraint for appropriate version (>= 0.10).
Merge branch 'master' into wip-update-optparse

Conflicts:
	retcon.cabal
	src/Retcon/Options.hs
Merge pull request #35 from anchor/wip-update-optparse

Update option parsing to work with latest optparse-applictive.