big enhancements: UDID, transcoder quality, …

- UDID added to every (?) XML, handled by WebServer, XMLConverter. This
should allow "private" settings for multiple aTVs
- transcoder: added quality levels 20M, 40M (do we really need that
much choice?)
- NavBar: re-added load by event
- utils.js: override stock loadURL functions to add UDID for
PlexConnect, collect other utilities.
- XML templates: added "utils.js" to support UDID. used URL() over
<path>ADDPATH().
This change affected  LOT of files. I am sure, I didn't test
everything… comments/fixes welcome.
Known issue: photo player - currently fullscreen doesn't work.