ported r248:252 from hidra branch:

ported r248:252 from hidra branch:

r248: much improved installation instructions, especially for Debian
      GNU/Linux distributions
r249: changed use of Spreadsheet::ParseExcel and MARC to require/import so
      that dependency on those modules can be resolved in runtime.
r250: finished installation documentation
r251: removing dependency on HTML::Parser would ease installation
r252: smaller eval{} fiexes. eval{} logic should really move to
      parse_format.pm

git-svn-id: file:///home/dpavlin/private/svn/webpac/trunk@255 13eb9ef6-21d5-0310-b721-a9d68796d827