Log Message:
Update to 3.8.0. Highlights from the changelog:

* Added the rhythmtapping modules.
* Added lessons to practise intervals from second to octave.
* Added twelve-tone and bpm exercises.
* Added ternary rhythm exercise.
* Added nameinterval exercise.
* Added descending melodic intervals exercise.
* Added LOTS of scale exercsies from Davide Bonetti.
* Removed GNOME dependencies. We now require pygtk 2.6.0 or newer.
* The user manual is now translatable using .po files.
* Many updated translations.
* Cairo version of all input widgets.
* Improved GtkTextView-based html widget if GtkHtml is not available.