Objects classified as other than STAR or EXTENDED are not written to disk

[rhl@…]

(Almost?) all of the pmSourceIO_XXX.c files contain a clause:

pmModel *model = pmSourceSelectModel (source);
if (model == NULL)

continue;

Looking at pmSourceSelectModel reveals that it looks at the pmSource->type
field, and returns NULL if it's not STAR or EXTENDED --- even if the source
has a valid model.

This is dangerous, as a mis-classified star (and I'm seeing c. 5% at 18th
in some SDSS fields) are silently discarded.

I do realise that bona fide cosmic rays should be ignored, but we need to
lean on the side of keeping junk, rather than discarding real objects.

[eugene]

done: these are now added to the output