Merge pull request #294 from codam/beta_debug

French tech updates + Zabojad latest modifications addition
optim when setting scroll left or top no need to update doc immediately
Merge branch 'beta_debug' of github.com:silexlabs/Cocktail into beta_debug
optimised text rendering loop
adding coordinate to clear method to clear a specific rect of btmap
adding dirty rect for rendering
improved dirty rect implementation
improved dirty rect implementation
reducing method calls
reduced calls to the background manager
reducing method calls
optimising
removed obsolete class
improved efficiency of floated element layout algorithm
small optimisation in core style
removed cascading of anonymous block which was useless
small optimis
removed calls to getTypedProperty
speeding up cascade
optimising rendering speed