Update SemanticWatchlist.php

Fixed constant
Clean-up

- Fixed #21
- Fixed #5 (Call to a member function getCount() on a non-object) because it broke a test
- Removed HookInterface (did not had any benefit)
Merge pull request #22 from SemanticMediaWiki/clean-up-after-i18n-merge

Clean-up
Update RELEASE-NOTES
Update RELEASE-NOTES
Update SemanticWatchlist.php

* Add license name to "Special:Version" which is supported by MW 1.23+. Will link to the COPYING file.
* Fix link for support
Merge pull request #24 from SemanticMediaWiki/license

Update SemanticWatchlist.php
Merge branch 'master' of ssh://wmfgerrit/mediawiki/extensions/SemanticWatchlist