[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Ability to define multiple plots of arbitrary types, through the new chart option "plots"
* Ability to configure existing special plots through the "plots" option given its name ("main", "plot2", "trend")
* Ability to configure each plot's visualRoles at the plot options level and of sourcing these from other plots' visual roles (by using the scheme "plotNameOrId.visualRoleName").
* Improved logging of visual role mapping information (as well as for the other log sections: data source, complex type, etc).
* Ability to specify extension points directly at the chart options level or at the plot options level, outside of the corresponding "extensionPoints" map.
* Changed the plot type of the normalized bar plot from "bar" to "nbar" (breaking change for some advanced uses).
* Reorganized the code:
  * consistent naming of files, uses a class suffix for better identification in a folder having different kinds of files
  * grouped files by visualization class, favouring the individual packaging of visualizations (in the path to AMD)
  * separated the pvc.data namespace into the "cdo" package (acronym for Community Data Objects), a sibling of "ccc" and "def".
  * split the giant pvc.js into multiple files.
  * moved some of the framework-related functionality in CCC to def.js
  * made it easier to update the "pvc.build.js" file by providing a script that converts the contents of "ccc-bundle-files.txt" into a JavaScript array "ccc-bundle-files.js", ready to copy&paste in the "pvc.build.js"

* Updated the code style
* Fixed an in the mean time revealed bug of the interpolation tests, that did not clear caches after changing the visible state of datums (the groupBy was previously done on a linked partData that now is spared of being created in some cases; there was no cache on the root level before).
* Fixed global leak in the number format tests, that left the global groupSizes changed, and affected other unrelated tests.
* Fixed an issue in the visual roles binding code that would prevent defaulting dimensions' properties from the properties of the single visual roles bound to them.
* Ability to not specify the "plot2" option, being sufficient to specify a spec for the plot named "plot2" in the "plots" option.
* New option legendVisible of visual roles. Allows hiding the legend group of only a particular plot and axis.
* Unit tests
* Options JsDocs
Merge pull request #97 from dcleao/CDF-287

[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Fix JsDocs category visual role missing from Point plots
Merge pull request #98 from dcleao/CDF-287

[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
Merge branch 'master' into CDF-287-prep

Conflicts:
	doc/model/charts/point.xml
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Fix labels derived by the translator from the column name not being capitalized and split into words.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Fixed pie plot not being able to do multiple plots because of the category and angle axes being shared. The fix is not optimal. Ideally we would want to be able to specify that an own axis (not shared, index auto/ assigned from negative values?) should be created.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Main site examples changes evidencing new features and ways of doing (plots, tooltip, formats)
* Grouped chart properties by component, making examples easier to understand and compare, and evidencing and transitioning to using plots and visualRoles collections.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* More changes to site examples. A new Pie multiple plot example.
* New pvc.finished helper function to make it easier to specify "finished" extension points.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Support for absolute extension prefixes in pvc_unwrapExtensionOne
* New helper function to generate random extension prefixes
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Fix Pie plot multi-line linked labels being too close.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Documentation rewording, regarding legend options.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Small change to be able to reuse a variable.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* Removed legacy/stale "hidden" def on the legend panel. Added the ability to hide individual items through extension point. No layout reflow though between sections.
[CDF-287] - As a user, I want to be able to define a chart made up of arbitrary, compatible, plots.
* A few file renames of files that weren't following the normal naming.
* Refactored the legend renderer classes.
* Removed "bullet" from the legend-related names.
* Changed the structure of legend scenes; now not following the one group per color axis and data cell rule; now, one color axis means one legend group; within the same legend group, multiple data cells may be present and each corresponding plot panel may register a legend symbol renderer.
* Visibility of the legend of a data cell is controlled by the corresponding visual role's "legend.visible" option.
* Legend symbol extension points can now be unambiguously specified in the color visual role's legend option object. This substitutes the existing "legend" + index, which are hard to know the indexes of; compatibility was maintained;
* Locking of legend items containing only trend datums, when in visibility clickMode, is now handled by the LegendItemSceneVisibility mixin.
* Added the ibits method to pvc.Interactive so that implementations may lazily calculate it; this was required to support the ability to not hide the last visible legend item.
* Updated unit tests relating to visual role's legend options.