Adds new buttons to the scene tree view.
Currently three new buttons are added
- Editor Comment: Every node that has a non empty editor_comment property will show up a sticky note icon. When pressed, this will select that node and open up the editor_description edit popup
- Incomming Connections: Every node that has one or more incoming connections will show up a "hearing ear" icon. When pressed, this will open a popup listing all current incomming connections to that node.
- Metadata: Every node that has one or more metadata entries show up a "sandwich" icon (three dashes). When pressed, this will open a popup listing the current metadata on that node.