Fix and improve Color documentation.
Completely rework event handling on view and tools.

Fixes multiple issues on iOS:
- mousedown events were sometimes fired twice.,
- the presence of mousedown handlers broke scrolling.
Closes #266.
Remove ill-named Matrix properties and replace with standardized a, c, b, d, tx, ty.
Start implementing mouse events on view.

Work in progress...
Improve Space examples.
Merge git://github.com/paperjs/paper.js