Issue 368: ON DUPLICATE KEY UPDATE did not work for multi-row inserts. Test case from Angus Macdonald.

MVStore: store root pages first; better size estimation for serialized objects; option to compress database content.

Memory usage calculation should also depend on the memory size of the value, not just on the number of pages.

There is a new Aggregate API that supports the internal H2 data types (GEOMETRY for example). Thanks a lot to Nicolas Fortin for the patch!