Move limting and skiping of results into class method

To speed up testing, the skiping and limiting of results
has been moved into a class method. Enabling testing of
the limiting and skipping code without excuting a full
query
`applySkip:andLimit:toResultSet:` perhaps? Putting limit before skip seems odd, and I'd like to move to using "ResultSet" in things like this -- I'll update my method names soon.