Set busy cursor on long job
Add instructions on setting environment variables in OS X
Bump firmware version for Kobo Touch driver

New firmware version released, updating versions to match.
Fixes #1245707 [Update to support Kobo firmware 2.10.0](https://bugs.launchpad.net/calibre/+bug/1245707)
Use <h2> for inserted ToC title for MOBI and PDF as well

See #1245076 ([Enhancement] Add PDF TOC Title, More Margin Options and ePub TOC Heading 1)
Remember window size of comments editor dialog
Start work on the editor component for Tweak Book