paper.translate(x, y)
Lets you modify the origin (zero coordinates) of a paper. An origin can also be passed to the options object of the joint.dia.Paper
constructor. If the method is called a "translate"
event is triggered on the paper. If the method is called with no paramater the current paper translate
transformation is returned.
paper.translate(100, 200) // set origin to `x=100` and `y=200`
paper.translate(100) // same as calling `translate(100,0)`
paper.translate() // returns e.g. { tx: 100, ty: 100 }