Ticket #12 : removed the previous hack-ish parallax layer code

Todo :
* implement the CSS -like repeat field (Ticket #124)
* update tutorial (Ticket #100) and documentation (html/github)
* clean-up any remaining messy code
* wait for the next Tiled release with official Image Layer Support
Ticket #124: added the "repeat" field for later reference (when working offline)
Added proper documentation for the `ratio` property
Stop using local copy of the library, and refer to parent directory for the last build
Ticket #100 : replaced obsolete "paralax" layers stuff by the new Image Layer

TODO :
* Update screenshots in the tutorial when an OSX version is available
(only windows nighty build are available for now)
Ticket #124 : fixed `repeat` variable scope
Ticket #100 : added missing ImageLayer Property screenshot (thanks @parasyte) and other documentation improvements
Ticket #100: update screenshot with something better matching the tutorial content (thanks Parasyte)
Ticket #100 : added back the missing Image Layer
Ticket #124 : add `repeat` property handling
Merge branch 'ImageLayer-cleaning' of https://github.com/obiot/melonJS into ImageLayer-cleaning
Merge remote-tracking branch 'origin/master' into ImageLayer-cleaning
getObjectGroupByName( )
Merge pull request #150 from vegar/master

Fix issue #149,#150  TileMap.getObjectGroupByName(name)
Ticket #148 : small updates to the README
Merge branch 'master' of https://github.com/obiot/melonJS
README update
added a function to test for rectangle equality
Updated to last version of closure compiler
Whack-a-mole example : disabled interpolation when scaling the display (or at least trying to)