* MolEnumerator: use repeat counts for SRUs when present #6429
This fixes the reported bug by parsing the SRU label to infer the rnage
of allowed repetitions.
* fix build failure from wrong field initialization order
* fix build error from -Werror=sign-compare
* add tests for molblock
* preliminary first pass at SRU enumeration
* handle HH
* working
plus add a missing file... <doh!>
* passes basic tests for enumeration of multiple non-overlapping SRUs
* more SRU testing
* explore combining the SRU enumeration with enumerate()
* first step towards RepeatUnit in the python interface
* first pass at directly connected SRUs
* Fixes#4561
* make sure we don't try to enumeration SRU + LINKNODE
update python docs
* exception for ladders
* get a bit smarter about rejecting linknode enumerations
* turns out we actually *can* do ladders pretty easily
* update java wrappers
* make sure we can input from CXSMILES too
* some cleanup/documentation
* some refactoring
* response to review
