safer and more readable.

function

possible, untangling the dependency between parameters 'ft->compare_fun' and
'ft->cmp_descriptor' in a sensible way. It is now much less necessary to
create a fake db (good) and some long parameter lists are now shorter
(it's a start)

each transaction's ranges instead of a hand-rolled buffer.

db->getf_set now perform zero mallocs. Also, move the is_temporary
bit into the cursor constructor.

functor instead of a macro for iterate.

rest of the code base

appropriate headers

This reverts commit d051cb71.

This reverts commit 467a5a99.

Variable key overwrite dmt

using different length (but equal) keys, using various overwrite methods
and interleaved aborts.