WIP: Add move away from point function and demo code

This merge request is a parked feature for 1.2, it adds a function to allow items to be moved away from or towards a point.

There are design decisions to work out for this feature:

• How should the feature be activated (comma and period keys with Shift held?)
• Should this be something you can do when resizing handles?
• Should items be modified with respect to their distance from the point or a fixed amount? (should all items move the same amount away)

There may be more considerations for the future.