GimpArray (and therefore the int32 array typedef) contains its own size.
We don't need to store the array size in a preceding argument.
Also adding gimp_int32_array_get_values() and gimp_int32_array_set_values()
to edit an existing GimpArray.
This comes with the fact we should start making the GimpArray type more
explicit, because clearly by trying to hide this type so much, it was
too much looking like the int32 array param spec was expecting a C array
(as was visible in the file-ico plug-in where we were getting a C array,
which was a bug only made invisible by the fact we were not setting the
C array back in the config object in the end).
Last but not least, I finally implemented int32 array (de)serialization.
As a side fix, the "images" arg in file-pdf-export-multi procedure is
now a proper image array (not an int32 array), and of course the "count"
arg was removed.
f2b9babfb4