BUG FIXES
* Improved audio input and output handling to fix problems on certain devices
* Tone ladder with absolute-do: The accidentals shown could be incorrect
* The "More courses" button was also shown on the Cloud login box
* Functional keyboard: Layout from a previous lesson is not shown when launching a new exercise
* Clapping exercises: for claps with wrong duration ("Evaluate note length") the evaluation was using gray instead of red
* ... and many minor adjustments and bug fixes