Allow Multiple layers of Conditional formatting with more flexible color options

[David_Elston]

Let conditional formatting options be stackable in layers (similar to MS Excel). In my current model we have a table that uses color across all cells based on the development stage.  At times we also want to color cells that have an error to a particular color of red, however this is not possible without stackable conditional formatting. 

Also enable the color formatting options that show up in chart options for conditional formatting.  The current formatting forces a small range of color options and certain colors cannot be used together.  Allow the model builder to select the 3 colors that go in the conditional format gradient in any order the like.

[tbeck]

Multiple Layers as well as a wider range of color combinations.

Ideally:

1) There will be more 2 color combinations with no colors (for 0's) and more colors as a second option.

2) 3 color combinations will have more middle values as blank and more color options on the left and right. 

3) A transparency option for visualization purposes.