Animate graph layout transitions

[automata]

Useful to better understand where nodes will be placed after an autolayout operation. Similar to yed's animations:

@forresto suggested that perhaps it could be done using CSS animations.

[forresto]

Frustratingly, that linked w3 proposal hasn't ​come to pass.

This proposal is to “promote” a subset of other SVG Attributes to “Presentation Attributes” or “Properties” for the purpose of supporting CSS features including transitions and animations.

We'll have to interpolate the svg x and y by hand in the rAF loop.

[bergie]

Animating could be handy also when browsing through the operations list of the undo/redo queue #23

[automata]

:+1: A simple add edge operation and I get lost:

I think animation can help with that.