Added support for multi-slot save files

Release overview and main changes

The same as in the original Citra-compatible release, but now the resulting save Checkpoint will include all the save slots. This is important for games like Monster Hunter 4 Ultimate where there is more than 1 save slot, resulting in 3 save files: user1, user2 and user3. The binaries in the original release only synced the first save slot, and now this is fixed.

Please read the following text from the original release for usage instructions, since it applies for this release too:

Original release text

Support downloading Citra saves from Dropbox into Checkpoint.

This requires using a 3DSync.ini generated from concreted.github.io/3dsync/ (not compatible with those generated from https://kyraminol.github.io/3DSync/).

Saves using this release will be placed in the Apps/3DSyncU directory in Dropbox, not Apps/3DS Sync.

The application will attempt to find and download Citra saves in Dropbox to the 3DS's Checkpoint directory. To enable, place your entire Citra sdmc directory in your Dropbox's Apps/3DSyncU directory. The final directory structure in Dropbox should look something like:

Apps
|_3DSyncU
  |_sdmc
    |_Nintendo 3DS
      |_...

Citra saves will show up in Checkpoint under each game with the name Citra.