* Added support to supply an X2 to bar charts to have them scale

* Fixed graph2d stacking issue.  It no longer takes into account hidden items

* Changed x2 to end per recommendation and added this to the docs

* Important performance enhancement supporting incremental changes to large graphs, these were too slow due to doing a full item conversion on each add().
Note: the data handling side of graph2d is currently somewhat over-engineered (=too complex) It can use some simplification....

* Fixed style based on feedback.

Cleanup of linegraph's event handling
Fixed #1557: Make sure we don't default to scientific notation.
Couple of minor fixes in group counts and ranges.

-Keep single defaults location
-Update documentation on formatting function.

Some fixes and cleanups after the large rewrite.

Provide the DataView.map() method similar to the DataSet one.

Add some enhancements for stacking (especially with regard to shading)

-Never push into arrays that have a known length
-Move more functions back into the main updateGraph method

Fix no-group data input case.

Separate shading from line drawing (fixes drawing order)
Cleanup of draw code
Fix icon-shading CSS override