Complete rewrite of groupstats.pl and NewsStats.pm.

Complete rewrite of groupstats.pl and NewsStats.pm.

* Switch to Getopt::Long, change coding style;
  limit line length.

* Replace 'die' and 'warn' by calls to &Bleat().

* Completely redo options and processing:
  - merge -m/-p/-a into --month
  - replace -i/-q/-d with - much more powerful -
    --group-by/--order-by
  - replace -t/-l with - much more powerful -
    --lower/--upper/--boundary
  - remove -b and replace it with --report

  Fixes #33.

* Add new report types, boundaries and sorting options:
  - report types 'average' and 'sums'
  - boundaries 'average' and 'sums'
  - upper and/or lower boundary
  - sort output independently

  Issue #35.
  Fixes #34, #38.

* Add possibility to cross-check newsgroups against
  checkgroups file.

* Complete rewrite of groupstats.pl internal logic:
  - modularize construction fo SQL queries
  - remove unnecessary special cases
  - refactor code into NewsStats.pm functions as much
    as possible

  Issue #37.
  Fixes #36.

* Rework output formats, fix padding problem by making use
  of modularized SQL queries.

  Fixes #15, #32.

* Add some more consistency checks.

  Issue #12.

* Redo documentation.

* Update TODO list.

Signed-off-by: Thomas Hochstein <thh@inter.net>