Sublime Text 3 support added. Default options changed. Default key bindings
changed.

* Sublime Text 3 support added. Most of porting to Python 3 has been done
  using information from http://python3porting.com/noconv.html.
* Default perltidy options changed. PerlTidy will now use the PBP set of
  perltidy options.
* Default key binding for OS X changed from `Command+Shift+t` to
  `Control+Shift+t`, the former fires a terminal.
* Options found in perltidyrc files will now override default/user options.
  The former processing of perltidy options was counter-intuitive. Old
  behavior can be restored by setting "perltidy_options_take_precedence" to
  "true" in user settings.
* Error output from perltidy is now displayed via class
  PerlTidyErrorOutputCommand, ST3 restricts editing of view contents.
* Fixed Python code used for bug reports and added helper script
  "helpers/create_issue_sys_info.pl" used to generate the required one-liner.
* Documentation updated, Package Control messages updated.
* Full changelog moved to CHANGES.markdown.