Issue#589 Support MERGE INTO ... USING syntax

issue#637: Oracle REPLACE(X,Y,NULL)

Fixed issue #497: TO_DATE reports invalid date format for correct format

Updated changelog

to_date failed to parse inline text - E.g. the "T" and "Z" in
to_date('2017-04-21T00:00:00Z', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')

Fix for "Change not-null / null -constraint to existing column" (MySql/ORACLE - SQL style)

Local.ENGLISH (if test system is not Local.ENGLISH).

Added readIfAll() to cope with all-or-nothing parsing for WHEN MATCHED THEN/WHEN NOT MATCHED THEN syntax

(MySql/ORACLE - SQL style)

Command failed silently corrupting the changed column.
Before the change (added after v1.4.196) following was observed:
 alter table T modify C int null; -- Worked as expected
 alter table T modify C null;     -- Silently corrupted column C

Adding french translation in _messages_fr.prop