missing include Net::Ping added

tags:
introducing ncopy

for ncopy to work, some code restructuring was done.

- all workers now support copy(), execute() and delete()
- load_modules() is now part of the Worker module
- more internal logic went from the worker modules into
  Main::callback_action()

tags: relevant
use Net::Ping instead of the command ping

tags:
ncopy was missing

tags: relevant
File::HomeDir dependency removed

tags: relevant
[sr]cp_user and [sr]sh_user was missing

tags: relevant
typo fixed

tags: relevant
mode local example added

tags: documentation
tags updated

tags: relevant
update
header: REFNAMES replaced by BRANCH

REFNAMES seems to be unreliable sometimes, better use BRANCH

tags: documentation
update
put_pubkey added

tags: relevant
no output was returned on timeout

tags: relevant
update
no output was returned on SIGINT

tags: relevant
LICENSE added

tags: documentation
hostnames can be given at the commandline

tags: relevant
typo fixed

tags: documentation
manual pages added

tags: documentation