Euterpe Version 8 update

This update includes a major feature and the first draft of the user manual.

The Mixer tab is the focus of this update.  Previously it did not respond to user input and only showed the current settings.

The Mixer now has complete functionality and responds to the sliders and mute/solo buttons.  In Edit and Loop Edit modes, changes to the slider controls are recorded.  In Loop Edit, real-time changes are recorded and added to the track at the end of the slider move.  In Edit mode, the setting at the end of the slider move is used; if a change event exists at the current position its value is modified, otherwise a new event is added.

A link to a rough draft of the User Manual has also been added.  It should be completed soon, although it is taking me longer to create than I had hoped.  Creating the manual is the main reason for the delay since the last update.

-J Werner