Preparing the Assistant Performer for use with Firefox 25

Refactored attribute.nodeValue to attribute.value in
Palettes.js because Firefox says attribute.nodeValue is
deprecated.
Latest versions of both Chrome and Firefox supported

Main change is that SVG-controls and -pages are no
longer placed lower down the main page. They are now
always at their correct position, but their visibility is
switched with the title and options.
All scores have been recompiled with improvements
discovered when loading them in Firefox.