Sharded map (work in progress)

git-svn-id: http://h2database.googlecode.com/svn/trunk@5625 e6896862-9d19-0410-bfb3-e9fa5d50e656
Reduce log output

git-svn-id: http://h2database.googlecode.com/svn/trunk@5626 e6896862-9d19-0410-bfb3-e9fa5d50e656
MVStore: in the multi-threaded mode, NullPointerException and other exceptions could occur.

git-svn-id: http://h2database.googlecode.com/svn/trunk@5627 e6896862-9d19-0410-bfb3-e9fa5d50e656