UI:
- Add menuitem to set zoom instead of left/right mouse clicking
- Modify VSS parsing to show stencil items on the page

Backend:
- Add support for version 5

BUGS/misimplementations/etc
---------------------------
- In some cases chunks have to be reordered
- EllipticalArc is not always correct
- groups.vsd rectangle is not white
- text is mostly oversized, paragraph splitting seems to work incorrectly
- text should not always had a border
- emf support is restricted (have to be enchanced in pymfvu and backported to vsdviewer)
