* Devise and implement a way for the plugins to register their
  configuration options and a suitable routine in Git::Hooks to grok
  them all. This would simplify plugin option processing.

* Implement the examples in https://github.com/schacon/githooks.

* Perhaps implement a kind of DENY for ACL operations, along the lines
  of NFSv4 ACLs (http://tools.ietf.org/html/rfc5661#section-6). I'm
  thinking about prefixing the what component with a '!'.

* Implement equivalents for the following SVN::Hooks
  (http://search.cpan.org/dist/SVN-Hooks/) plugins: DenyFilenames,
  UpdateConfFile. Actually, I'm thinking that UpdateConfFile is too
  much specific. Perhaps something along the lines of this post-update
  hook would be more interesting:
  http://stackoverflow.com/questions/279169/deploy-a-project-using-git-push.

* Let the user tell which configuration files Git::Hooks should
  consider. Currently it considers the three default ones (system,
  global, and local), without knowing which one sets what. Perhaps we
  could have a new option "githooks.extra_config" that could be set
  with an array of filenames to invoke "git config --file" with in
  succession. This option, if set in the default configuration files,
  could tell Git::Hooks to grok an extra set of configuration from
  specific files.

* CheckLog.spelling should have a way to register stopwords. I'd have
  to ask for a change in Text::SpellChecker.

* CheckLog should check the footer of the commit log message. The
  Gerrit default commit-msg implements some checks that could be used
  here. Some other things to check:

  ** Require Signed-off-by lines
     (https://github.com/icefox/git-hooks/blob/master/git_hooks/commit-msg/signed-off-by)

  ** Duplicate Signed-off-by lines
     (https://github.com/icefox/git-hooks/blob/master/contrib/commit-msg/duplicate-signedoffby)

* Implement a hook to make it easy to perform some checks on
  added/modified files. For instance, Perl files should be syntax
  checked. This could be configured somewhat like this:

  CheckFile.rule "\.p[lm]$ perl -c"

  The first 'word' in the value would be a regexp used to match the
  files we're interested in. All that follows would be a command to
  which the filename would be passed.

  This would allow for all kinds of checks specific for some kinds of
  files. Some interesting ideas here:
  http://tech.yipit.com/2011/11/16/183772396/.

* Implement a hook to check the safety of rewrites, by detecting when
  we're ammending or rebasing commits that have already been
  pushed. Some discussions about this:

  ** http://git.661346.n2.nabble.com/pre-rebase-safety-hook-td1614613.html

  ** http://git.apache.org/xmlbeans.git/hooks/pre-rebase.sample

  ** http://www.mentby.com/Group/git/rfc-pre-rebase-refuse-to-rewrite-commits-that-are-reachable-from-upstream.html

  ** http://git.661346.n2.nabble.com/RFD-Rewriting-safety-warn-before-when-rewriting-published-history-td7254708.html