Added query parser draft in datalayer.
Fixed error when raising SyntaxError in datalayer query parser.
Added function, tuple, list and repr support to datalayer Query.
Added support for attributes in datalayer Query.
Added support for various types in datalayer Query.
Added base class for datalayer elements and equality operator overload.
Added some empty test cases.
Merge branch 'unstable' into feature/datalayer
Fixed datalayer query parsing.