improvements to AbbaLockingDetector

git-svn-id: http://h2database.googlecode.com/svn/trunk@5674 e6896862-9d19-0410-bfb3-e9fa5d50e656
reduce unnecessary object allocation of date/time types

git-svn-id: http://h2database.googlecode.com/svn/trunk@5675 e6896862-9d19-0410-bfb3-e9fa5d50e656
Fix bug in dividing very-small BigDecimal numbers

git-svn-id: http://h2database.googlecode.com/svn/trunk@5676 e6896862-9d19-0410-bfb3-e9fa5d50e656