Let OMVRBTreeRID and OMVRBTreeRIDSet classes implement ORecordLazyMultiValue interface
JSON: disabled pretty print by default to sabe precious bytes
Updated Binary protocol to rel. 15 supporting SET types natively

Until rel. 14 LIST and SET were stored in the same way using []. Now
Sets are stored as <>.
mvtbtree: supported case when serialized object was in form of list []
Minor: changed test for asynch query
SQL:  fixed context problems
Merge branch 'master' of https://github.com/nuvolabase/orientdb