Hides unrelated tabs from the metadata view

The content cover, references, and history tabs are now hidden.
It is also possible to hide the Categories and Attachment tabs using
InterceptionPoints (SiteNodeVersionEditor.[Categories, Attachments]).

This commit also introduces a setting for defining the content type
to use for Meta infos.
Updates text and format of del. noti message

Also fixes a miss in the IG2 merge where the force delete button
had the wrong label.
Merge pull request #72 from stenbacka/delete-noti-mail-updates

Updates text and format of del. noti message
Fixed a few issues with copy page. For one it's now possible to copy to itself. Also better messages on error,
Improved the drag&drop-based sort/move. Much more stable and clear.
Merge branch 'master' of github.com:bogeblad/infoglue
New icon for move
Merge pull request #73 from stenbacka/hide-tabs-in-metadata-view

Hides unrelated tabs from the metadata view