* [DEPR] The HeatGrid option 'scalingType' has been deprecated in favor of the new 'colorScaleType'.
* def.js features:
   * Added ECMAScript5 shim of "Function#bind"
   * def.base is now placed in this.base of instances during overriding methods execution (same syntax as Base.js).
   * an 'override' method is added to every def.type created class. It allows for a nice per-instance method override with "this.base" support.
* [FEAT] New chart option "compatVersion" allows for better backward compatibility. Currently the single value 1 is supported and causes the chart to *try* to behave like CCC "version 1".
* Null value support has been improved:
  * The null atom of each dimension is only created when effectively used (a new Virtual Null Atom is used in cases where it is needed - in null datums - when a real null datum is not created).
  * The null atom of each dimension is now included in its atom list. The null atom always sorts first in ascending order.
  * The methods pvc.data.Data#{groupBy, where} now let null values in grouped by or filtered by dimensions to pass-through.
  * The series that is automatically added when the data source has no series, and a chart requires it, is the null-atom of the 'series' dimension or of the default dimension of the series role.
* [FEAT] Dimension types can be defined as "isHidden"; hidden dimension types are not shown in the default tooltip; this feature allows control or auxiliary dimension types to be defined.
* [BREAK] The MetricLine and MetricDot charts no longer sort data by the base (x) values. This same behavior can be achieved by specifying a comparer function for the "x" role dimension type. The option compatVersion = 1 may come to provide this previous sorting behavior (currently not implemented).
This behavior defeated one of the key abilities of "metric" charts - plotting data points that have some relevant order - for example drawing an ellipsis or parabola with dots and lines.
* [BREAK] The charts pvc.mStackedLineChart and pvc.mStackedAreaChart were removed.
These charts behaved in a similar way to the currently existing, non-"metric", pvc.StackedLineChart and pvc.StackedAreaChart(they both support continuous (numeric and date) base axis).
Note that *stacking* presumes grouping on the base axis' values - the categories - and *summing* the series values of same categories. The distinctive characteristic of "metric" charts is that there is no grouping on the "base" axis. Grouping on the base axis is a feature of *categorical* charts - data is grouped by *category*. Categories may be of continuous value types (in which case it represents a quantization of the continuous domain)...

* pvc.data.Complex now includes a 'value' property whose value is that of the 'key' property - when the complex has more than one local atom, or the value of pvc.Atom#value - of the single local atom. This property is used to feed scale functions in an uniform way, whether a role is discrete or continuous, and of single or multiple dimensions.
* [FIX] (Atom GC after load) Fixed a bug caused by the "null" datum filtering that is done upon data translation/loading. Atoms that had been interned solely because of datums later excluded would be left in their dimensions, as if used by some datum. This bug affected the correct detection of the use of the dimensions' null atoms.
* A few more data.compat.js functions aren't needed anymore and were deleted.
* [FEAT] Crosstab translation in "seriesInColumns" format correctly handles the case where there are no series (S = 0). No "auto-series" dimension is created.
* [FEAT] New pvc.color.scale function that creates a single color scale of discrete, linear or normal-distribution type (supports "color" role of XY Scatter).
* New debug level 4 - verbose
* New base class pvc.Cartesian2DAbstract between pvc.TimeseriesAbstract and pvc.CategoricalAbstract.
  All axis related logic, not related to "categories", has been moved from pvc.CategoricalAbstract to pvc.Cartesian2DAbstract.
  The new pvc.Cartesian2DAbstractPanel inherited all of the code of the now "deceased" pvc.CategoricalAbstractPanel.
  New class pvc.visual.CartesianAxis encapsulates all axis related logic, helps in determining axes options, and makes scale creation code much more clean.
* Renamed pvc.MetricAbstract to pvc.MetricXYAbstract
  The pvc.MetricScatterAbstract was renamed to pvc.MetricLineDotAbstract and inherits directly from pvc.Cartesian2DAbstract.
* LineDotArea has been changed to include the new "Sign" and "Scene" constructs, and the derived "Area", "Dot" and "Line".
* The MetricLineDot chart has been (totally) rewritten, taking lessons (and code) from LineDotArea