Grammar documentation: Extracting columnName from "Column Definition" for reuse in ALTER TABLE ALTER COLUMN.

problem report and fix by lubomir.benes on the  h2 mailing list

Date parsing logic assumes that the calendar type is Gregorian, so it should use the Gregorian calendar even if the default locale says otherwise.

Fixes #675

on table containing more than one LOB column

This reverts commit e26337e9.

seems to cause various unit test failures.