0.60.0

• Expansion state of collapsible plug grouping is now remembered for the duration of a session (#87).
• Current tab in Node Editor is now remembered for the duration of a session (#87).
• Fixed a bug in the NodeGraph where setTitle() was having no effect.
• Slowed wheel zooming (#200).
• Fixed crash when dragging nodes (#211).
• Improved NodeEditor node labelling (#151).