Same for gimp_procedure_add_aux_argument() and gimp_procedure_add_return_value().
We now have specific public functions for every supported type and it's
in fact much better to use them. The generic functions gave the feeling
that we could use any GParamSpec as procedure argument, whereas we in
fact depend on what the PDB support, and only these subtypes.
Changes only to ScriptFu.
The third term (the default) of a SF-FONT etc. spec is now ignored.
Test case is SF>Test>Sphere. There are still crashing issues
related but separate.
Why: puts most methods for SFArg (a struct) in one place, for ease of maintenance.
Prepares to fix issue 8328. Prepares to make SF use GimpProcedureDialog.
Mostly moving code, with no intended change in functionality,
except fixed an property.nick for an arg is now what a script author provided,
instead of generated.
All internal to libscriptfu. No changes to the exported API or to i18n.
Lightly tested, since more substantive changes coming for issue 8328.
ScriptFu>Test>Sphere is the test case.
