Change dependency type to unordered-containers
Switch from `Map` to `HashMap`

This is in preparation of Aeson, and only want one type of Map data type.
Because converting between the two is too much hassle.
Make an alias type for repeated Sections
Do the same with repeated Languages type
Merge branch 'hashmap' into json-storage
Move language definition into separate json file
Add languages.json to data-files
Add aeson to dependencies
Change interface to fit the Language type
Merge branch 'json-storage'
Version bump to 0.6.2