DNS views, part 18 (1 of 2)

Issue #26
User interface: search

This commit provides:
- search host or IP address

Changes:
- add domain capability to the nmuser class
- add an HTML class for easy and parametric HTML writing
    (first draft with only mask/unmask link)
- inclusion of the mask/unmask javavscript code in htg templates
- first (and incomplete) work on the search CGI script