This reverts commit 2d4b87f0.

The reverted commit leads to the following regressions:

 - Basic dialogs
   (which were not targeted, but impacted, by the reverted commit)
   with several RadioButtons sharing a group-name (as they will have a
   tendency to do) cannot be loaded anymore, since the implementation
   assumes (and checks) that names are unique.

 - Even in forms, where a RadioButton had both a form:name and a
   form:group-name attribute, the form:name attribute wins and thus
   RadioButtons that has the same group-name but different form:name
   (as they will tend to do) will not anymore be mutually exclusive,
   which defeats their point.

Additionally, since it did not change the UI parts (property editor
window), the user was still presented with two different editable
properties "Name" and "Group Name", where "Group Name" was empty...

Change-Id: I1bff532a5a7336cf2eb0579bcd4e2d16be6480fe