Adding support to stacked bars

[dynaum]

I just modified the bar graph to render bars stacked.

[brunograsselli]

👍

[tiraeth]

LGTM. Please prepare a separete example file and revert bar.html to the original one. This will allow Olly to merge changes with one click :-)

[dynaum]

Done!

[oesmith]

LGTM! 👍

[gamov]

This is great but I feel the following improvements are needed:

• in the label there should be a total value displayed (of all the series)
  For Bar in general:
• an option to display the value below the top of the bar segment.

eg: http://www.htmldrive.net/items/show/754/Beautiful-CSS-Stack-Bar-Graphs