Custom color/format creation

[nicolaje]

On @benEnsta suggestion, add a command to create named custom colors or format from the client.
RGB and RGBA are heavy to use, therefore we could add commands to create custom named colors or formats:

vibes::addNamedColor("myRed",(vibes::RGBA){255,0,0,50});

vibes::drawBox(0,1,0,1,vibesParams("FaceColor","myRed"));

vibes::addNamedFormat("myFormat","FaceColor","myRed","EdgeColor",(vibes::RGBA){42,43,44,45},"LineWidth",1,"LineStyle",":-"));

vibes::drawCircle(0,0,50,"myFormat");

[nicolaje]

Afterthought:
if the goal is to not have to manipulate RGB/A structure, why not set a group property? Are there use cases (readability of the code?) where we would need named colors instead of group properties?