* Editor: Include the main editor-popup-menu into the
  bottom of the track-header popup menu.
* Edit: Button to "reverse song" (i.e. all reverse
  all blocks).
* Edit: Fix the functions to reverse notes. They
  weren't very good before.
* GUI: Highlight tab elements when mouse hovers
  above.
* GUI: Add JUCE version to the About-window.
* GUI: Increase default height of message window
  somewhat.
* MIDI learn: Fix incremental mode when recording
  automation to editor.
* API: backwardsSong.