Docs updates
Correct description of github-fork-ribbon plugin
Add offline download to TiddlyWeb control panel

Add button to download an offline-compatible snapshot to the TiddlyWeb
control panel
Docs updates
Remove duplicate header

And provide a slightly more informative prompt
Fixed problem with insertBefore() method in fakedom

Was preventing refreshing of widget trees built against the fakedom.
Add quick build

For testing it’s handy to be able to build index.html quickly
Refactored stylesheet implementation

This way we reuse the refresh mechanism properly so that theme tweaks
can be applied interactively.