Fixes errors introduced by my prior commit c0ca0b74
1. SF is storing colors in GimpRGB, not GeglColor.
Storing using wrong pointer type seemed to work, but would not build on newer compilers.
2. spurious error message "CRITICAL....Two different plugins tried to register..."
Due to calling gimp_ui_init too early, in the class instance init.
For version 3 scripts, using script-fu-register-filter
Widgets for SF-OPTION and SF-DIRNAME
Fixes#9992
Test case is Sphere v3.
Note that SF-VECTORS is still not supported,
until there is a VectorsChooser widget in libgimp.
A step towards deprecating old-style scripts using script-fu-register,
and deleting script-fu-interface, the duplicate dialog for SF.
But we still need to change or replace script-fu-register (for non-filter plugins)
to use GimpProcedureDialog.
This goes with our planned change of not making GimpProcedure arguments order
relevant anymore regarding the PDB API. In particular, it means we don't want to
use GimpValueArray for various procedure arguments API, but directly
GimpProcedureConfig objects.
This change will allow to add or reorder arguments in the future, so that we
won't have to create new PDB procedures when adding new arguments, while still
keeping PDB API stability.
Resolves#8382
Also v2 scripts infer and set sensitivity to drawables
Add two test plugins clothify-v3.scm and test-sphere-v3.scm.
Temporary, to be removed when 3.0 ships.
Some refactoring (extracting methods, moving functions to new files).
Some drive-by fixes to script-fu-arg.c revealed by using GimpProcedureDialog.
bootchk