Dupes: Move common code out of Add and log warnings

* Argument path listing will be used by other modules
* No need to print errors directly to stdout when there are better options
Dupes: Create new "Keep" command

* Currently is not able to actually discard dupes, it just prints them
Merge branch 'master' into dupes
Remove unused imports in Command.Dupes.Keep
Remove usages of TemplateHaskell from main executable

* This will allow building on platforms like arm that do not support ghci
* Cleanup unused dependencies
Merge branch 'dupes'

Conflicts:
	src/Command/Dupes/Add.hs
	src/Store/LevelDB.hs