Reworking title filtering

What I don't like about this module's current implementation of filtering
for titles is that for nodes (comment title filtering not being part of the
module) a title that contains words in the filter list is rewritten and saved
into the database with the replacement word.

I think the filtering model for the node body is the correct one in that the
original text is stored and filtered on node load. This allows for changes
in the replacement text or even temporary replacement that is lifted
at a later time.

I've attached a patch that implements comment title and body filtering
and refactors node title filtering to instead alter the title on either node
load for viewing or after node save for insert/updates.

While this does mean that the node or comment title is rewritten
_in the context of other modules_ that implement hook_nodeapi
and/or hook_comment for the load/insert/update/publish operations
it is still better than the outright replacement and storing of the
title with replacement text in the node or comment at node or
comment save time.