Fixed a typo in describe helper
Added trigger_action parsing and linking actions
Added linking support and helpers

* Added link/unlink action
* Added linking helpers (type detection, mixins, attrs etc.)
* Renamed methods in create_helper to avoid naming conflicts
Minor version bump to 4.2.0.beta.5
Normalizing source and target for links (relative)
Added highline as a dependency again
Minor version bump to 4.2.0.beta.6
Merge pull request #22 from arax/cli_fixes

CLI update - part I.