Added support for root features in the product editor.

* When a new feature is added. The default install mode is "root
* Installmode is visible in the feature label
* Properties contains a field to set the install mode
* A button is added to toggle the root mode
* toggle root mode first sets all modes to the same value (true)
* then when all selected are equal mode, it toggles.

Change-Id: I505afb234dd71c17cf28ab3fff0c7eca22a3e5b0
Signed-off-by: Wim Jongman <wim.jongman@remainsoftware.com>