ClipPath more advanced use cases

Nesting clipPaths

One problem of clipTo and usage of canvas.clip() was that you could not have more than one clipPath at time.

With this implementation clippaths can have their own clippaths. While this is less intuitive to program manually, it allows to intersect clipPaths togheter.

ClipPaths in objects inside groups should be isolated from the clipPath of the group itself:

Clipping with Text

Clipping with text was not possible with clipTo too, dev had usually to fallback on patterns for that