merged internal methods 'native_api()' and 'select_qsa()' into 'client_api()' and renamed it 'select', reworked a bit the code of both 'select()' and 'match()' for size, added better error handling for cases when passed selector is not valid, added missing declaration of XMLMatchers object
merged internal methods 'native_api()' and 'select_qsa()' into 'client_api()' and renamed it 'select', reworked a bit the code of both 'select()' and 'match()' for size, added better error handling for cases when passed selector is not valid, added missing declaration of XMLMatchers object

dperini/nwmatcher,dperini/nwmatcher,dperini/nwmatcher