Add thumbnail in the EXIF tag of JPEG picture not having one (batch processing)

Features

- Add thumbnail to pictures (JPEG) that don't yet have one
- Lanczos algorithm to downsample picture thanks to [FFmpeg's swscale library][2] for best results.
- Select one or more folders to scan from any storage (internal, SDCard...). For example DCIM, Pictures...
- Exclude one subdirectory from selected directories
- Preserve timestamps of the pictures
- Processing log
- Synchronize deleted files in the