Craedl

Setting rescan=False on directory uploads and downloads will completely skip over directories that have transferred successfully in the past. This will ignore any changes to these directories in order to jump to the point where it left off previously (in case of failure, e.g.). Leaving rescan=True (the default) will rescan all children looking for changes everywhere.

-use a directory content time stamp hash to determine whether it is necessary to check the contents for upload
-store the hashes in a sqlite3 database for both upload and download

- use a directory content time stamp hash to determine whether it is necessary to check the contents for upload
- store the hashes in a sqlite3 database for both upload and download

Patched a bug in the upload ignoring files that start with '.' or '~'.

Upload and download using local log files for skipping work that was already complete was fast but allowed for differences between local and remote copies to appear. This removes the local log file tracking and communicates with the remote to ensure synchronization.