Fixed a bug affecting the implementation of draggable paths
Fixed a few bugs and added a few features

- Fixed a bug which caused layer events to fire twice
- Added a new 'canvas' property for easier access to a layer's canvas
element
- Added a new 'data' property, an object for storing user-defined data
on any jCanvas layer.
Added a jQuery plugin manifest file for the new jQuery plugins repository
Fixed version number in plugin manifest
Fixed a parse error in the package manifest
Tweaked package manifest
Updated build script
Fixed build script
Corrected a typo in the package manifest
Merge branch 'master' of https://github.com/caleb531/jcanvas