Sequence bugfixes and AJAX pacer.
All ZMenus pointed to same variant in flanking seq.

Explicitly remove v parameter.
Changed text to be consistent with menus and buttons
Changed instances of 'datahub' in user interface to 'trackhub'
Added new fieldset so we can show a different label on the trackhub URL input
Merging commit from pull request (from master)
Update label colours to have a slightly better render with the new sequence highlighting
Text sequence legend fixes.
Text sequence legend fixes.
Fix broken BLAST sequence views.
Fix broken BLAST sequence views.
Sequence key bugfixes.
Sequence key bugfixes.
Emty key removal. Again!
Emty key removal. Again!
Add more info to the deprecated warning
Add more info to the deprecated warning
Changed button text to 'Download alignment'
Disable download when no alignment chosen
Change the title of the hover menu too