any-selector first trial

raises exception Not_found from parsers.ml, line 519
The way of data extraction must be analysed in more depth...
any-match function created; but so far selection does not work.
tagselect-argument renamed: "any" -> "anytag"
corrected "any" to "anytag"
function "find_any_elements" added
Merge branch 'master' into tagselect_any
now using the new extractor-function for elements.
collect_singles / extract_pairs: now element-doclist as parameter.
anytag-selector for tagselect-command.

:-)