moving global headers into one top-level location

[Tor Lillqvist]

> If swui is a proper lib on top of sw, it should either:
> - be a toplevel module on its own

As somebody who ~never touches sw, I find this a good, clean, idea;)

The sw, sd and sc modules are so large anyway, that if they in fact
can be split up into logical sub-parts, those could well be separate
modules, too. Just IMHO.

The "module" concept no longer has the organisational meaning it
perhaps had in OOo, no new "project" with Lead and Co-Leads is needed
to be set up to introduce a new module etc;)

> - our we should introduce "submodules" properly, in with case we could clean up
>   the huge messy flat toplevel and instead have only some ~ten top level dirs,
>   like external/ ure/ core/ writer/ calc/ draw/ base/ extensions/ ...

That might be even better.

--tml