Significant improvements

- Centre of Mass is now limited to just the split view
- Added buttons for undo/redo
- Moved suspension settings to the wheel view
- Moved appearance settings to the body view
- Moved “help” to “Extra -> Help”
- Merged load/save view into one “saves” view
- Ripped out the update system (will not be in v2, sorry remi!)
- Updated website URL
- Renamed help to about