1.0.0-rc.6

Release 1.0.0-rc.6

- Fix crash after remesh
- Fix remesh memory leak
- Change default part base as PartBase::Average
- Add menu to Parts Tree: Refresh
- Remove short menu from Parts Tree
- Fix part widget display at wrong place
- Fix deformMap of imported document not saved
- Fix UV not generated if only uncombined or errored components exist
- Optimize nodes deletion
- Remove Mark Pen