v0.12.0

expansion of values in set

New features:
- expand settings in value of set
  commit b0ac6fdda6a492ce11244e7af4c06217eb7697e0
- expand environment variables in value of set
  commit 0c24886db4ca9dfd41b07b5400aaa50c3cdea40b

Changes:
- moved format_value, parse_value and expand to ConfigFile in order to improve customizability
  commit 788548c35f66bc5125c30066289958e67c995b29
- moved get_completions_for_file_name to ConfigFile in order to improve customizability
  commit c1c2684fdc2c0e9acfeddb7b3ef4db76d7480f49