Fixed problem with importing tiddlers with double quotes, gt, lt etc

Reported by @giffmex
Refine formatting of tiddler links

See TiddlerLinks for details
Extend the edit widget to be able to edit properties of data tiddlers
Add a theme tweaks panel

Themes can define their own theme tweaks tiddler
Correct typo in 954a987d31b89232abbebb28974f80e932046f07
Move the animation duration into a tiddler so that we can easily let it be adjusted in the control panel