[office] Updated work plan proposal

Dear TC member,

I've updated and attached the work plan proposal to better reflect 
Daniel Vogelheim's work packages proposal 
(http://lists.oasis-open.org/archives/office/200301/msg00027.html)

The changes I've made are,

- styles and formatting attributes are now a separate chapter,
- meta information will be discussed earlier,
- packages are now a separate chapter.

In the work packages proposal styles are in front of graphic content. To 
avoid discussing graphic styles and formatting properties before the 
graphic content itself, I moved styles behind graphic content in the 
working plan.

Best regards

Michael