Added negative value support
Cleaned up code and made some optimisations
Got rid of some random extra tabs
Improved support for decimal numbers
Corrected a typo
Added ability to specify width and height

Added the ability to specify the width and height of the canvas for
circumstances which require the graph be rendered while the canvas is
not visible to the user.
Fixed group labels not drawing since the rewrite
Added new examples to the demo
Merge pull request #2 from rastating/misc/demo

Misc/demo