Redmine

Hi!

I added some features to hook.rb:

• cleaned-up call_hook

• added an :if option to render_on, so you can write:
  

   render_on :view_issues_form_details_bottom, :partial => "test", :if => :really?

• added render_to_string to ActionMailer so call_hook can also be called from the mail templates in app/views/mailer

Unfortunately I didn't manage to write the matching test for @hook_test.rb" so far.