GitLab

- removed a lot of redundant code (especially in install/uninstall/list)
- some operations should be reimplemented using the generic functions
  in the `arduino/libraries` module.
- improved output of `lib list` command
- improved indexer

Fix #145

This field will keep the information coming from the package_index.json.

It would be better to keep the index and the current status in two
different trees, BTW this is a major refactoring and will be done in
the future.

This will be used in the library manager (right now the indexed
libraries are mixed with installed libraries)

The new function does not involve parsing of the FQBN that is now done
inside the specific object method.