[metapost] MP docs

[Taco Hoekwater]

Hans Hagen wrote:
>>
>> The user-friendly solution were to have 'black' and 'white' behave as an
>> rgbcolor /or/ cmykcolor depending on the context, but I don't know if
>> that is possible in MetaPost.

No, but it could be a greyscale, as Hans proposed. But I am not sure
that that is a good idea. The whole point of also having greyscale
and CMYK color models is to have more control over color conversions.

I you want 'ease of use', you can just keep on using RGB just like
in previous versions (and pray that the postprocessing RIP does
something sensible).

> no need to specify cmykblack and cmykwhite, more natural is to map black 
> and white on gray scales; postscript rips are supposed to handle this ok 

It is still useful. A color can be .5cmykcyan + .5cmykblack.

> 
> somehow withcolor expects (numeric) but i may do something wrong

grey levels are bare numerics, yes. It seemed silly and over-complicated
to introduce a <type> for a <single value>.

Best wishes,
Taco