Move boost::uuid into wrapper class, improve build speed by 20%
Merge pull request #183 from bastih/feature/move_uuid_boost_to_single_compilation_unit

Move boost::uuid into wrapper class, improve build speed
adding Operations to GroupByScan
* >as< to specify the name of the resulting aggregation column
* >min< and >max< as new operators
* >distinct< option for count operator (naive distinct)