Super-mega-huge update before 1.x goes obsolete

* Modified less.js to revert data-uri's to url's
* Added a tab context menu with various close options
* Implemented correct "goto line" inside editor

* Added "Edit" context menu with "Select" \ "Find" \ "Goto Line"
shortcuts

* Added "Save on Crunch" and "Enable \ Disable File Monitoring" options
(& in preferences)
- See issue matthew-dean/Crunch#61
- See issue matthew-dean/Crunch#46

* Improved preferences handling (code-wise)
* Improved less.js version detection

* Slightly modified keyboard shortcuts & updated appropriate section in
"Help"
- See issue matthew-dean/Crunch#52

* Fixed matthew-dean/Crunch#76 - Esc now works for closing both
dropdowns
* Fixed matthew-dean/Crunch#44 - Search field now keeps it's value
* Fixed matthew-dean/Crunch#37 - Ctrl+W \ Command+W now closes the
current tab
* Fixed matthew-dean/Crunch#77