WIP: paper.js integration

[rksm]

This is work in progress and the outcome of a weekend project.

paper.js is a HTML canvas JS library that supports
vector-style canvas rendering. Since our current path / polygon implementation
that is SVG-based suffers from the issues that arise when combining SVG /
HTML, this might be a a replacement.

Usage:

require('apps.paperjs').toRun(function() {
    var path = new apps.paperjs.Path([pt(0,0), pt(20,10), pt(100,100)]);
    path.openInWorld();
});

[bgnk]

Nice, that approach seems to be fast and robust.
Now we just need a pen tool and some bezier handles and we could really get it going in the graphics department :)

[bgnk]

When the path is rotated (through the normal Lively rotate), moving one point influences the positions of the others.
Maybe the problem can be found here somewhere?

[rksm]

Yeah, we could apply the morphic transformations here to fix that behavior. However, I thought that it might be even better to change how rotation is done for paperjs morphs by using paperjs transformations and rotate the paperjs objects on the canvas itself... for simple usage of lines/curves the current behavior should be OK, though.

[rksm]

bezier handles: nice thing is they come for free as paperjs draws them when a paperjs item is marked "selected". Unfortunately their style is not yet customizable.

[calmez]

This is super cool. I would like to use that for the SyncMorph in the Webwerkstatt.