AppCache Complete

AppCache is fully integrated in Gltn. Everything works online and off.
3rd party panels and themes? Continually downloaded and saved into
localStorage, recalled when Offline == true

Also, notifications were added today after I felt bored for half an
hour. It's fairly rudimentary, and only works with AppCache for now.
It'll be interesting to see what developers do with it.
-Fixed bugs that didn't load data in the correct order, sometimes
leading to corruption
-AppCache messages more accurate
-Panels now can be set to a service specifically
-Improved function for keyboard shortcuts, plus a parameter added to
install_panel()