Improve isSimpleIdentifier() and enquoteIdentifier()

Improve DATABASE_TO_LOWER handling

Fix NPE in TableFilter.createIndexConditions()

Fix newlines in test scripts

Delay creation of index conditions for ON conditions to avoid NPE

Add more context-sensitive keywords

Use Sequence.flush() in AlterSequence to avoid concurrent update exception

Fix concurrent deletion handling in SELECT FOR UPDATE

Assorted changes

Fix DISTINCT ON in presence of ORDER BY

Fix window functions in JOIN with ON condition