3.0.0-beta

Still a bit rough around the edges, but it is finally out.

A lot of changes:

• AMD compatible
• responsive default theme
• switched to LESS (compiled css is there of course)
• grunt build system
• in memory data model (a lot faster on large trees)
• passes jslint
• JSON is now in the core as it is the most used data format
• support is from IE8 and up
• dropped XML plugin (can easily be ported though)
• and a lot of other stuff :)