Fixes jsTree's relative URL construction for theme components

Calculates the path component of the URL used to load cms.changelist.js
and sets jsTree's settings.ui.theme_path relative to that.
Fix whitespace, remove '?' from script selector.

The '?' which was removed would cause the selector to only find the
<script> tag if cms.changelist.js had been specified with a query
string following it.
Fixes typo in documentation
Sideframe is not shown (Google Chrome, Mac). display: block and no one changes it

Hi, I'm not sure whether it's a bug or some kind of feature, but in my case I coulndt make the sideframe appear, but as soon as I added this little show() method everything was working as it should.

Can you please take a look at it?

Kind Regards
Fixed relative imports on Python 3.
Using "undefined" instead of "null" to load/unload jQuery (toolbar.html)