make fromHSL public, add toHSL

[Olaf Schmidt]

[ Thomas Zander, Mi., 13. Jun. 2007 ]
> > No, there was no consensus in this,
> Sure there was;
> read this again;

There was a discussion on whether a public HSL colour space is needed for 
blending. Some people (Zack, you) argued that it is not needed, Matthew (and 
maybe some others) disagreed. "Consensus" means that everyone agrees. For the 
record, I agree with Matthew but read the thread too late to speak up at the 
time.

In the meantime we had other discussions on this list about
a) allowing Windows users to use the colour space they are familiar with, and
b) doing proper colour contrast evaluations as defined in the WCAG 2.0 
standard (which is useful outside of khtml).

I am not sure whether the HSL colour space which Matthew suggests to make 
public is actually identical to my sHSL colourspace for colour manipulations 
and contrast evaluations, but if it is, then I see no need to have several 
implementations of it in parallel.

If I misunderstood Matthew here, then I withdraw my objection.

> Sorry for being a bit agitated, but its that I am getting a bit tired of a
> weekly thread of Matthew asking again and again and again for public
> KDELIbs API for this color space.

I also apologise for my agitated response. I am grateful that Matthew puts so 
much energy into fixing colour-related accessibility problems (using HSL) and 
into implementing the recommendations we have made.
Please do not attack him for doing so. He has my full support. It was my 
failure to the overlook the earlier threads, not Matthew's.

Olaf