Miscellaneous mailer.py cleanups.
Miscellaneous mailer.py cleanups.

* tools/hook-scripts/mailer/mailer.py (main): Do not test 'author' in the
    commit case, since it will always be None.
  (OutputBase): Bind the StandardOutput and MailedOutput classes under a
    common abstract base class. Abstract the subject-prefixing code here.
  (StandardOutput, MailedOutput): Derive from OutputBase.
  (MailedOutput.mail_headers): Subject line creation moved out to base class.
  (StandardOutput.start, SMTPOutput.start, PipeOutput.start): Remove the
    inconsistently applied and never used '**args' parameter.
  (StandardOutput.start): Print the "Subject" line, even though we are not
    sending email, as it contains useful summary information.
  (Messenger.__init__, Messenger.determine_output): Inline determine_output at
    its only callsite, __init__.
  (Commit.__init__, PropChange.__init__): Remove incorrect fixme comment.
  (PropChange.__init__): Remove redundant assignment.
  (Config.is_set): Remove unused variable 'parts'.
  (initialization code): Don't initialize 'action' with a meaningful-looking
    value - 'M' - when in fact the default will never be used, and the
    initialization is simply a declaration of the variable. Clarify that some
    variables are for propchanges only.
  (TODO comments): Remove those items marked [DONE].


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@852419 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion