Decouple plot order from legend order

[Henrik_Volkers]

I would like to have the plot order decoupled from the legend list order.

Currently the first (data) plot is top on the diagram and top of the legend list.

Cool would be  two new properties per plot that define how the plot order and the legend order has to be sorted.

A bonus would be special values like <Always on top> (=0)  <Always on bottom> (+INF for watever datatype choosen I32?) , with a documention how conflicts are solved.

Proposal:

Starting in data provided order 

- if a number or <Always on top> is provided,  it will be placed at that index in the list and shifts all other down

- <Always on bottom> (the default value to keep the old behaveiour) just add to the bottom,

Or make all positions default 0 and start sorting from the last data entry .... or ... 

To reduce the inflation of properties one list for plot or legend order would be sufficient and the data order would define the other .

[fabric]

At a minimum I'd like the ability to reverse the z-order of the plots relative to the legend. Generally I want Plot 1 to render on top of Plot 0, etc... (The default behaviour is for Plot 0 to render topmost.)