Major improvements to distribution index loading.
Implemented new transitional UI for startup.
If **no** distribution index is loaded on startup, completion of startup will be prevented and the user will be shown a message displaying the issue.
Launch errors are now shown as overlays.
Many more minor fixes and enhancements.
Moved server selection styles to launcher.css, as they are nearly finished.
Moved overlay convenience functions to overlay.js.
Moved launch area (landing.ejs) convenience functions to landing.js.
Various cleanups and documentation also added.