Admin: Remove unused messages and topicicons views (code cleanup)

Unfinished features should be kept in their own branches.
Admin: Change models to use more Joomla standards
Merge remote branch 'upstream/master'
Small post merge fix
Merge remote branch 'upstream/master'
Merge pull request #1404 from mahagr/master

Admin: Remove unused messages and topicicons views (code cleanup), model work