0.17.0

• Enforce a limit of 3GiB on keys & values
• Fix database corruption bug that could occur if a Durability::None commit was made,
  followed by a durable commit and the durable commit crashed or encountered an I/O error during commit()
• Fix panic when re-openning a database file, when the process that last had it open had crashed
• Fix several bugs where an I/O error during commit() could cause a panic instead of returning an Err
• Change length argument to insert_reserve() to u32
• Change Table::len() to return u64
• Change width of most fields in DatabaseStats to u64
• Remove K type parameter from AccessGuardMut
• Add Database::compact() which compacts the database file
• Performance optimizations