I made a silly mistake in a database wrapper where keys
were sorted by char instead of uint8_t. As x86 char is signed
the sorting for the block index database was messed up, resulting
in a segfault due to missing records.
Add a test to catch:
- Wrong sorting
- Seeking errors
- Iteration result not complete
Pass parent wrapper directly instead of obfuscation key. This
makes it possible for other databases which re-use this code
to use other properties from the database.
Add a namespace dbwrapper_private for private functions to be used
only in dbwrapper.h/cpp and dbwrapper_tests.
