Minor tweaks to the OpenHMIS project diagram.

* doc/openhmis.dia: Make some of the lines dashed, as they should have
  been in commit 0f9b1d12a.  Use relative path to reference `www.svg`.

* doc/www.svg: New file.  Apparently Dia files does not carry images
  internally, but just reference them at whatever path is specified.

* doc/openhmis.png: Regenerate.