Revise and refactor dojox.color.Generator

[Tom Trenka]

The current implementation of Generator, while effective, attempts to generate too many colors per algorithm--resulting in a set of tints per palette that is too subtle for easy distinction between palette members.

Based on conversations with Eugene, we've decided that we're going to revise the Generator to do the following:

• Follow kuler's lead in only/always generating 4 colors per base color passed (so that there will always be a total of 5 colors);
• Allow a user to define their own 5 color palette and use it for manipulation purposes;
• Create a set of additional functions that allow for transformation of a palette; transformations might include shifting hue, saturation and luminosity, or a combination thereof;
• Allow for the application/definition of alpha channels, with alpha transformation as well.

This will probably result in a new dojox.color.Palette object, with a set of manipulation functions (i.e. dojox.color.Palette.transform) to manipulate a palette. Think Array for colors.

Once this is complete, convert dojox.charting to consume this object (including the possibility of using transform to generate gradients). This task will be a separate ticket.

[Tom Trenka]

Refs #7260 (convert dojox.charting to use this).

[Tom Trenka]

(In [14628]) Fixes #7259. New Palette object with better palette generators and transformations. !strict.