At script create time, create a GimpRGB i.e. pixel from the declared name of default color.
At plugin procedure registration time, convert that pixel to GeglColor,
and use that color to declare the color arg using GeglParamSpecColor(default=color)
Fixes a faulty fix a few commits back where we lost the declared color name.
The proper dataflow is name->color->paramspec-with-default-color.
Extract methods related to color into new file.
So method names document what is being done.
So related code is together.
Ditto for resource.
No functional change.
Preparing for changes to reset/default and changes to representation of pixels
in lists of differing lengths rgb vs rgba.