update cron.buildd to use a filelist exported from the db rather than adirectory scan.  update apt.conf.buildd to match.

* vars: external-overrides variable added* cron.daily: Update testing/unstable Task: overrides from joeyhmanaged external source.

Normalize reject messages and tone down dpkg-sucks ones.  Add new check for Build-Depends: ARRAY breakage.

Move clean_symlink here.  New function wrap().  Don't bomb out on bogus blank lines when not using dsc_whitespace_rules.  don't bother validating arguments in send_mail.  minor improvements to rejection messages in check_signature().  Other minor changes.

use EXISTS (SELECT 1.  when looking for un-suite'd binaries and source exclude stuff with an existent last_used.