code cleanup
ref #7923 Extract common interface for feature tree editors
ref #7837 Make feature tree export experimental
ref #7837 Add docx export to feature tree context menu
Ask for saving before executing operations
ref #7010 Adapt feature tree handlers for multiple selection
ref #6746 Hide menu items when nothing is selected
ref #6746 Add/adapt handlers for feature tree editor
ref #6746 Add details view for feature tree and feature node
ref #6806 Add context menu to feature tree editor