0.11.0

• Remove [u8] and str type support. Use &[u8] and &str instead.
• Change get(), range() and several other methods to return AccessGuard.
• Rename AccessGuard::to_value() to value()
• Add a non-mmap based backend which is now the default. This makes Database::create() and
  Database::open() safe, but has worse performance in some cases. The mmap backend is available
  via create_mmapped()/open_mmapped(). There is no difference in the file format, so applications
  can switch from one backend to the other.
• Better handling of fsync failures