implementations for one single centered canvas with automatic scaling
save images in one max size (can be set to original image width and hight (ratio has to be 1 to .8 -> set larger side to 1))
automatic drawing of canvas-content to clones
copy to clones on resize
implementations for undo and redo
implementations for undo
implementations for redo (undo vs redo still to do)
comments for canvas class
two strategies implementation for undo & redo
keybindings implemented (using mousetrap), added new version of jQuery
template update
merge from master