Function: recolor_image

--Usage--
> recolor_image(input: image, color: color)

Re-color an image:
 * Red is replaced by the color
 * Green is replaced by black or white, of the same lightness as the color.
   So if the color is light, green will be replaced by white.
 * Blue is replaced by black or white, of the opposite lightness.
 * White stays white, black stays black

This function is mostly intended to make symbols in a symbol font wich can match the text color.



--Parameters--
! Parameter	Type			Description
| @input@	[[type:image]]		Image to recolor.
| @color@	[[type:color]]		Color by which to replace red.

--Examples--
> recolor_image("symbol1.png", color: rgb(180,0,0))      ==  [[Image]]
>>> recolor_image(<img src="symbol1.png" alt='"symbol1.png"' style="border:1px solid black;vertical-align:middle;margin:1px;" />, color: rgb(180,0,0)) == <img src="symbol1_red.png" alt='"symbol1_red.png"' style="border:1px solid black;vertical-align:middle;margin:1px;" />
> recolor_image("symbol1.png", color: rgb(100,255,0))  ==  [[Image]]
>>> recolor_image(<img src="symbol1.png" alt='"symbol1.png"' style="border:1px solid black;vertical-align:middle;margin:1px;" />, color: rgb(100,255,0)) == <img src="symbol1_green.png" alt='"symbol1_green.png"' style="border:1px solid black;vertical-align:middle;margin:1px;" />
