added hint how to preserve foreign tapes

Fixes #351: Detect and refuse to write Label on LTFS formatted tapes
tweak console help message

Issues #181: Add command for doing a name resolution on client
Make sanity check configurable.

Use some macros for setting the minimum and maximum size
of an Hello message used for protecting our connections into
the SD and DIR.

This also fixes the problem for the console director message
which can be shorter then 25 bytes.
Fix problem with *all* acl.

We more or less ignored this setting for named consoles. Probably a side
effect of the adding of the auditing. So we didn't ever allow access
which we should have done.
Fix python-fd save packet flag handling.