Control tab modeling

* Modeling of the Control tab.
* New Accordion Tree code. (separate from the original one)
* Expression editor mixin
* Refresh button mixin

What has been done
* Log tab
* Events (complete, including links to the PolicyViews)
* Policies (expression editor, condition editing, condition assigment editing, event assignment editing, adding new policies, deleting policies ... seems complete). The expression editor is not covered completely as it changes between the pages. This should be modified later, but Field, Count of, Tag should work everywhere. Things like Registry or Find are not fully covered.
* Conditions (they use basically the code from Policies which is shared among them).