Made a setting for using native or custom scrollbars
fixed hack so switching between native and custom works correctly
Add native scroll bars preference to default preferences.json.  Also add command and menu option to toggle the preference
Merge pull request #438 from TheKiteEatingTree/scrollbars

Toggle Native Scroll Bars
Turn relative common.js requires into absolute ones so that loading the
same module with different relative paths results in the same module.
Update submodules
Added treehugger to zed/lib for sandbox, includes a parser for
JavaScript and Python (currently). May have to factor this out later.
Python parser is used for an improved Python mode (currently reports
parse errors with semantic analysis in the works).
Work in preparation for preferences UI.
Added new preference UI
Work on removing the project picker
Work on a unified interface.
Work
Work on making stuff work again with new system.
More tweaking of the UI
Fix drag and drop
More tweaking of layout, colors etc.
Make it look reasonable on Mac and Linux
Fix standalone version CLI stuff.
Key refactoring, important changes:
* Add cursor below/up is now Ctrl-Shift-Up/Down (instead of Ctrl-Alt)
* Add cursor on next/prev instance is now Ctrl-Shift-]/[ (to be more consistent with Ctrl-[ and Ctrl-])

In addition a lot of Alt- based keys were added familiar for vim users, e.g.:
* Alt-h,j,k,l,0,$,^,w,b all do what a vim users expects (and versions with Shift are the selection versions).
Added Select:None command.