Great refactoring of "Repository Manager"

- [x] Create a `RM` namespace for all the repo manager stuff
- [x] Move existing classes to own directory
- [x] Move `RepoMan` into `RM` namespace
- [x] Rename `RepositoryInfo` to `Repo` and move it to `RM` namespace
- [x] Abstract base object for all RM objects
- [x] Separate data and internal logic from public interface
- [x] Create global event interface
- [x] Access to a context menu per object
- [x] Provide icons per object (We can make nice overlays for those icons, later)
- [x] Write event catcher for testing
- [x] Integrate `Repo` with the `Base` object
- [x] Write cached abstraction layer for references
- [ ] Write event catcher for debug output
- [ ] Unit testing for `Repo`

---
__Note__: this branch is currently rebased on top of `feature/viewsmenu` (in `libHeaven` and `libMacGitverCore`)