Also, unify the checkNow and checking menu items, as there is no Cancel anymore

This is not a part of the extension, just an extra utility.

* This runs "apt-get --simulate autoremove" in a script to find autoremovable
packages

* Add update check
* Remove some duplicated strings

* Some bug fixes
* Fairly stable Synaptic-like behaviour:
  - New packages in repository
  - Local/Obsolete packages
  - Residual config files

This imitates the information one can get from Synaptic

- New packages
- Local/Obsolete packages
- Residual config files

Added Cataland and updated Spanish