depositfiles (upload): add new upload method

The websites uses a new upload method which this update
implements. It now uses some kind of non-public API.

Since the old methods still seems to work fine
(in most cases) the new method is only used when the
user requests this with "-api" option.
jheberg (list): fix, upstream modified
doc: add plowprobe man page

+ small english refactor
+ add plowprobe in Makefile/setup.sh