Fixed issue with possible >4GB corrupted files after upload.
Improvements:
When using -onlydiff with the command put, S3Express now calculates the MD5 value of local files only if a matched file name on S3 is found. This speeds up the comparison and upload.
-onlydiff now working also for large files >4GB.
New MD5 calculation for multi-part upload mode matching the Amazon S3 calculation.
-nomulmd5 option of command put now used only for files <1GB to speed up upload.
-nomd5existcheck of command put now used only for files <200MB to speed up upload.