preparation for extraction-list of tagselect-cmd
basic extractor-functions seperated from retval-creation.

A first step to rebuild the stuff, so that it can be used with
extractor-lists also.
tagselect prepared for extratcor-lists.

Data-collection for the extracts prepared with a List-fold.
try_tagselect mores systematically - now matching succession of extractor-agrs in main.ml
show_match in atrctor-löist-test and simple reformatting for readibility
extractor-lists for single-extaractors available now :-)
unused stuff removed
extractor_t is now splitted into Single_extr and Pair_extr
Merge branch 'extractor-list'