Add 3D bar chart implementation and slide example

[loictro]

It adds the 3D bar chart feature.
Most of the existing chart options should be well rendered.

• The following options are specific:

Name	Description
bar3DShape	box (default), cylinder, coneToMax, pyramid, pyramidToMax
barGapDepthPct	Bar gap depth (default 150)
serAxis*	All Category axis parameters but for Series axis
serGridLine	Series grid line style (same as catGridLine and valGridLine)
v3DRotX	[-90, 90] X rotation (default: 30)
v3DRotY	[0, 360] Y rotation (default: 30)
v3DRAngAx	true (default) or false Right angle axes
v3DPerspective	[0, 240] Perspective (default: 30)
dataLabelBkgrdColors	true or false (default) If true the data label background color is set to the series color

An example of 3D bar charts with some of the specific options is added in the HTML demo file. (Slide 6 of charts).
The generated file is OOXML valid and seems to open well with Microsoft Powerpoint 2010!

[gitbrent]

Thanks very much for the new charts @loictro !