We now try to emulate cairo_t:
We keep a stack of nodes via push/pop and a transform matrix.
So whenever a new node is added to the snapshot, we transform it
by the current transform matrix and append it to the current node.
Includes the ability to turn on updates in the inspector. Animations are
now run via a tick function which allows us to neatly overlay a
semi-transparent red rectangle and fade it out over time.
It also probably enables way more, but somebody with more UI neatness
than me needs to figure out what it eanbles first...
