Excluding <reply> and <action> from random factoids

Added an exclude_verb param to lookup() to exclude
a list of verbs from the search, and used it in
the random factoid picker
Don't spit out an error message if volunteering a factoid

Added a "ignore_empty" parameter, set to 1 if volunteering
the factoid.  The "literal" command handler checks for this
and is silent if it's set.
Moving verb exclude list into config var

random_exclude_verb, to be precise
Merge branch 'ignore_empty'