Added options to customize tilted pie shadows.

Fix makeCanvas for IE, broken by Retina support introduced in 179d2e1d.

Fixed a typo.

Update links to point to flotcharts.org.

Fix typo

Project links have changed.

Cast tick label to string prior to `replace` call

In the edge case that an actual integer, or other non-string, is passed as a label, it must be cast to String before `replace` can safely be called.

The recent changes to add retina support included a call to getContext
made before excanvas/flashcanvas had a chance to register their hooks;
fixed by moving that code up a few lines.

- Minor code cleanup and comments describing how we use pixel ratios.

Basic retina display support

Auto-generation of legend colors no longer results in only white and black above a certain number of series.

As the size of the variation increases, the resulting colors approach
white and black. To avoid this we now reset the variation when it gets
too large. This results in repeated colors, but that's much better than
a list full of whites and blacks.

Linked the errorbars example to the examples index page, and cleaned up
both the example and documentation at the top of the plugin.

Added a plugin to generate error bars.

Allow custom highlight color