Bugfixes and improvements

Bugfix: OracleStatementSemanticModel - nested function calls resolved
correctly now
Improved: OracleSqlParser - added new terminal option -
AllowQuotedNotation - "COUNT" is equal to COUNT; because of specific
grammar rules for specific built-in SQL functions
Added: OracleSqlParser - support for KEEP clause, e. g., SELECT
MAX(SELECTION_ID) KEEP (DENSE_RANK FIRST ORDER BY RESPONDENTBUCKET_ID)
FROM SELECTION
Added: OracleSqlParser - support for FIRST_VALUE/LAST_VALUE IGNORE NULLS
clause, e. g., SELECT "FIRST_VALUE"(SELECTION_ID IGNORE NULLS) OVER (),
LAST_VALUE(SELECTION_ID) IGNORE NULLS OVER () FROM SELECTION