rename the newly introduced UNDO_LOG_SIZE column to CONTAINS_UNCOMMITTED, because that is more reliable than the size of the undo log

git-svn-id: http://h2database.googlecode.com/svn/trunk@5050 e6896862-9d19-0410-bfb3-e9fa5d50e656
javadoc updates: there is no need to explicitly document thrown exception unless it provides some extra commentary

git-svn-id: http://h2database.googlecode.com/svn/trunk@5051 e6896862-9d19-0410-bfb3-e9fa5d50e656