Changes in version 1.6:

A major code reorganization has been undertaken.

This version skips faster over damaged areas after two consecutive
errors have been encountered.

A new pass has been added that trims error areas backward before splitting.

Support for sparse writes to the output file has been added.

Blocks longer than sector size are now split at sector boundaries.

The new option "--fill" has been added.

The new chapter "Fill Mode" has been added to the manual.

A "current status" line has been added to the logfile.

This version can resume an interrupted retry pass instead of reinitiating it.

This version achieves perfect resumability if interrupted during
trimming or splitting.

Handle also SIGHUP and SIGTERM (like SIGINT) to allow clean interrupt on
connection loss or system shutdown.

The "--quiet" option also quiets error messages.

Print a more informative error message when reading an old logfile.

A note has been added to the manual about old logfiles.

Consistency checks have been added to detect possible bugs.
