* Create an exact bit (#818) for the sums (but doesn't calculate it.)
 * Add magic to the file header (#22)
 * Add per-subdb dupsort flags. (#333).

Did
{{{
$ cd tokudb
$ svn merge -r3990:4094 https://svn.tokutek.com/tokudb/tokudb.818/
$ cd ..
$ svn delete tokudb.818
}}}


git-svn-id: file:///svn/tokudb@4095 c7de825b-a66e-492c-adef-691d508d4ae1