Another batch with a lot of internal updates, yet no visual changes to the
site:

- watchdog (rewrite):
   + the collected information provides more details and insights
     for post-mortem research
   + input limitation
- database abstraction layer:
   + mysql errors are now verbose and is no longer displayed in a
     browser - fixes a possible security risk
- admin.php:
   + updated watchdog page
   + fixed security flaw
- diary.php:
   + fixed nl2br problem
- themes:
   + fixed comment bug in all 3 themes.
- misc:
   + renamed some global variables for sake of consistency:
      $sitename  -->  $site_name
      $siteurl   -->  $site_url
   + added input check where (a) exploitable and (b) possible
   + added input size check
   + various small improvements
   + fixed various typoes

... and much, much more in fact.

This significant commit fixes 99% of all known bugs and improves drop.org
by means of better security checks in order to avoid malicious behavior.
In addition, quite some code has been fine-tuned.

However, as a result, every theme will require a small update ...

A really BIG, BIG UPDATE, after two straight days of nothing but code
and sleep, new stuff is finally in drop.org.  This is a quite large
and wide-ranging update, which affects almost all of the system files
in one way or another.  I fixed quite a lot of bugs and added quite a
lot of new features, mostly administrative tools as these were really
lacking.  It's far from finished but it's a start ...

  http://beta.drop.org/foobar.php
  (The customized error pages need to be beautified.)