Review and refinement

this "refinement" got a little bigger than expected ... :smile: please see commits for more details (and check gcc) - last 3 commits of master where discarded by merge.
tagged for todo: GLbitfield operators, update shell script for unix, compare glew example and qt example
please specificly review and discuss: 
* query class, 
* sets in meta, 
* separate enum classes for featured enums and bitfields (instead of just forwarding), 
* overall structure, 
* extensions-test (code generation of extensions and features needs to be re-evaluated),
* default option configuration