Version 1.6.3 released

- Rollback to TinyMCE 4.0.8. Reason: the 4.0.9 version has bugs.
- Keep the previous option to select which style properties to keep when
pasting a Microsoft Word document
- Add an option to modify the behaviour of the Mce Insert command to
automaticaly scrolll down to the bottom of the inserted element.
- Fix a bug with IE/Jquery when inserting a XenForo attachment inside
the editor