Sync MDB To 93802f26a (NOTLS)
Turn on MDB_NOTLS by default.
Add cffi version of 'transactionless' API.
Add transaction management section.
Fix the wrong.
Add docs for initial_readers and spare_readers.
Stricter more CPython-friendly interface.
Docs harder.
CPython implementations of all but deletes/cursor().
Erroneous decref.
Implement Environment.deletes().
Implement Environment.cursor(). This leaks the env object somehow.