[Libreoffice] Undoing basis/brand split in 3.5

As recently announced on #libreoffice-dev, I consider undoing the 
basis/brand layer split.  Historically, this was introduced at Sun to 
make it possible for various products (plain OpenOffice.org, Brasilian 
BrOffice re-branding, Sun's proprietary StarOffice, ...) to share code 
that is only built, packaged (into platform specific package formats 
like rpm, deb), and quality-checked once.

With LibO today, there is no real need for that split any longer, so it 
only complicates our code base.  I would undo it in incremental steps 
directly on master (unless I hit temporary problems that cannot be 
worked around easily and that force me on a branch of my own).  One 
consequence would be that the 3.5 package and file system layout would 
differ rather substantially from the 3.4 one (so that, e.g., using some 
form of delta packages to upgrade from 3.4 to 3.5 would not be a good 
idea, if anybody wanted to do something like that anyway).

(There is also a URE/rest split, which I will not touch for now.  At 
least Debian seems to be interested in having a stand alone URE on top 
of which sits a LibO alongside potentially more apps.)

So, if you see any issue with this, please make yourself heard.

-Stephan