Repository ftp/htp sync gives poor feedback and isn't performant

[ThosRTanner]

Ideally, upload/download ftp (in async mode anyway) should

• work out how much data it as to transfer and give a progress report based on that, raather than the 'transferred 1 file, transferred 2 files' system it has currently.
• write file to disk as it receives data from network (or vice versa) rather than reading file into / writing file from string
• read/write both files at once (async only!)