Improve the redirect context processor test.

* rename the context processor used from 'custom' to 'broken'
* remove the custom middleware, because it is not used in the context of
  the test
* rename the test to better identify what it is testing
Work around spurious mousemove on Chrome.

When clicking on an element in Chrome, spurious mousemove events can be
generated when the cursor hasn't actually moved.  This can prevent the
toolbar from being shown when the handle is clicked because the code
sees the mousemove event and thinks a handle drag is happening.  Work
around this by only running the handle drag code if the cursor has moved
since the mousedown event.
Make the pain go away.

Fix #581, #544, #541, #535 and a few others.
Merge pull request #587 from living180/work_around_chrome_mousemove

Work around spurious mousemove on Chrome.
Merge pull request #586 from living180/improve_redirect_test

Improve the redirect context processor test.
We don't minify CSS and JS any more.
Update source translations.
Update translations.
Minor update in release process.
Bump version number.