Link associated rule deletion with estimate deletion
Add deletion of associated rules for estimate tree deletion
Fix display of associated rules for no-estimate selection
Merge branch 'task/rule-deletion' into qt-rewrite
Clean up icons directory
Add 48x48 oxygen icons as resources
Add support for platform-specific icons
Improve look of toolbar

The previous implementation used multiple toolbars for file, edit,
and analysis actions. Since none of these toolbars were moveable
or floatable, there was little reason to keep them as separate
toolbars. By moving them to a single toolbar and adding separators
between the action groups, the visible separation is clearer
(especially on look-and-feels that did not display a verticle line
between toolbars).
Merge branch 'task/icons' into qt-rewrite