DNS views, part 18 (2 of 2)

Issue #26
User interface: search

This commit provides:
- simplify result page (by masking some informations)
- result page provides links to edit some data
- search for groups
- mechanism to restrict search to some object types
    ("group: test", "host: www")
- capability to handle more object types (future use)
- check message uses
- check message translations

Changes:
- change search form parameter from "crit=" to "q="
- add group management to the nmuser class
- add allowed-groups procedure which returns ids of groups
    allowed to modify an IP address
- complement display-rr with a uniform interface to
    provide links
- renames html-host-info to display-rr-masked in order
    to clarify role and function
- simplify nextprog/nextargs mechanism in the add CGI
    script, such as capability to add a sequence of
    addresses is handled by the script itself and not
    by the nextprog/nextargs mechanism. As such, adds
    an optional "naddr" form parameter
- provides capability to return to previous search in
    add/del/mod/edit CGI scripts, via nextprog/nextargs
    mechanism