Small YAML dumping tweaks
Small YAML dumping tweaks

- Allow specification of "Dumper" parameter for yaml.dump in the YAMLDumper.
  Has limited use but as I wanted to implement the rearrange command this way
  I considered this to be "not bad" and just let it be.
- Add the ``plistlib._InternalDict`` to the dumpable objects of yaml.SafeDumper.
  Removes the need to create a new dict for every instance.

SublimeText/AAAPackageDev,SublimeText/PackageDev,SublimeText/AAAPackageDev