Bugfixes and improvements

Added: OracleSqlParser - MERGE statement support
Bugfix: OracleSqlParser - LATERAL subqueries are correctly parsed now,
e. g., SELECT * FROM LATERAL (SELECT * FROM DUAL)
Bugfix: Nested parenthesis and (+) are correctly recognizes, e. g.,
SELECT * FROM TABLE(((DATABASE_ALERTS(+))))(+) VALID_ALIAS