more whitespace cleanup, comment and improve image_get_filename code so it doesn't look like a crasher bug

the last commit deleted the old flext files. I didn't realize git automatically puts deleted files with a commit, otherwise I would have done this all in a single commit

 *merged improvements in Fred Jan's new branch of cyclone with pd-l2ork's improvements

(manually ported)
*added @pd_help in addition to the existing @pd_extra that can be used for paths
*made pddplink capable of parsing @pd_extra and @pd_help
*updated cyclone help files to make advantage of the @pd_extra/@pd_help paths in order to reference global help file documentation

(selective port):
 *fixed cyclone bugs in cartopol~ and poltocar~
*gave coll optional argument to determine whether it should be threaded or not