tuned defining of no headings desired for lister

LmiLister now accepts COLUMNS property with empty list or tuple
assigned. It means that no headings shall be printed and no header names
are excpected from associated function to be returned. This is different
from using FMT_NO_HEADINGS. Note the following table:

  COLUMNS    FMT_NO_HEADINGS  headers printed  assoc-func return headers
  not empty  False            yes              no
  not empty  True             no               no
  None       False            yes              yes
  None       True             no               yes
  []         False            no               no
  []         True             no               no

Note that headers printing field may still be controlled by
--no-headings option. This the correct name for 3rd column would be
"column headers can be printed".
hardware: fixed declaration of listing commands

Due to a change in handling of COLUMNS and FMT_NO_HEADINGS, the correct
way to disable printing column headers with LmiLister command is to
set the COLUMNS to empty list/tuple.
software: tuned usage message

Documented one missing option and clarified repo listing command.
service: prettified error descriptions

Related to trace ticket #237
netwoking: tuned declaration of lister commands

Semantics of COLUMNS property changed a bit for LmiLister command.
It affects just those wanting to suppress column headers completely.
Although previous declaration works, it defines column names that are
never used, which does not make sense.