Add delay between scroll event and highlight

This prevents scroll events schedule even more highlights and
resulting in strange scrollbar rollbacks.

Fix #36
Merge branch 'fix_scroller-jump'
Fix -hidePreviewPane: after swap; update style
Fix menu entries wording to reflect behaviour
Add Amornchai Kanokpullwad as contributor
Merge branch 'zoonooz/master'

Fix #49
added shiny new preferences icons
added me to the contributors in credits
slightly changed the brightness of the icons
Comply to 80-column rule
Add WIP style guide
Implement start home key

Fix #51
Merge branch 'home-key'
tweaked "Editor" and "Markdown" preferences icon
Tweak the icon ever so slightly
Merge branch 'alexkaessner/master'
Add more language aliases

c++             -> cpp
coffee          -> coffeescript
coffee-script   -> coffeescript
cs              -> csharp
js              -> javascript
json            -> javascript
py              -> python
rb              -> ruby
sh              -> bash

All alises except "json" are based on Atom's mapping.
https://github.com/atom/language-gfm/blob/master/grammars/gfm.cson

JSON is not JavaScript, strictly speaking, but they are similar
enough and is offered for convenience.

Close #56
Register self as editor for public.text

Fix #54
Override +writableType to only return Markdown

So that user won't be able to save a new document to .txt
Override +writableType to only return Markdown

So that user won't be able to save a new document to .txt