Item12664: working towards release of new NatEditPlugin

details:

- fixed editing topic preferences
- removed inline style attributes in headings
- implemented date picker but disabled it for now
- add dependency on SetVariablePlugin for Foswikis < 1.2.0
- added compatibiltiy wrapper handling strike one on different Foswiki engines
- 



git-svn-id: http://svn.foswiki.org/trunk@17281 0b4bb1d4-4e5a-0410-9cc4-b2b747904278