Data type: statistics dimension

--Overview--

A dimension or axis for the statistics panel.

One or more dimensions are combined in a graph, these combinations are called [[type:statistics category]]s.

Statistics dimensions are automatically generated for all card fields in a [[type:game]] that don't set @show statistics@ to @false@.

Categories are also automatically generated from dimensions.

--Properties--
! Property		Type			Default		Description
| @name@		[[type:string]]		''required''	Name of this dimension, used as an axis label and a label for automatically generated categories.
| @description@		[[type:string]]		@""@		A description of the dimension, currently not used.
| @position hint@	[[type:string]]		@0@		Hint for ordering dimensions.
| @icon@		[[type:filename]]	 		Filename of an icon for this dimension.
| @script@		[[type:script]]		''required''	Script that generates a value for each card in the set.
| @numeric@		[[type:boolean]]	@false@		Is the value always a number?
| @show empty@		[[type:boolean]]	@false@		Should cards with the value @""@ be included?
| @split list@		[[type:boolean]]	@false@		Indicates the value is a list of the form @"item1, item2"@. The card is put under both items.
| @colors@		[[type:map]] of opaque [[type:color]]s	 	Colors to use for specific values
| @groups@		[[type:list]] of [[type:string]]s	 	Values to always show, and the order to show them in.

--Example--
Automatically generated statistics dimensions look like this:
>statistics dimension:
>	name: power
>	script: card.power

Specify a specific order and color of values, otherwise they are ordered alphabeticaly and groups with no cards are not shown:
>statistics dimension:
>	name: color
>	script: card.color
>	group: white
>	group: blue
>	group: black
>	group: red
>	group: green
>	colors:
>		white: rgb(255,255,255)
>		blue:  rgb(0,0,255)
>		black: rgb(0,0,0)
>		red:   rgb(255,0,0)
>		green: rgb(0,255,0)
