[GSoC 2012][Collaboration] ScDocFunc and Collaboration

Hello calc guys,

I have ~two questions about ScDocShell, ScDocFunc and Collaboration.

I am working on moving sc/source/ui/collab/contacts.* into tubes/
There will be new Collaboration abstract class in tubes/ and something
in sc/ should implement it.

First:
1, Why we have new ScDocFuncSend( *this, new ScDocFuncRecv( new
ScDocFuncDirect( *this ) ) ); chain ?
It could be just one class as long as it inherits from ScDocFunc I think.
Also ScDocFuncDirect is just ScDocFunc with own costructor, not sure what for.

2,
For class ScCollaboration : Collaboration there are two possibilities I think.
a, We will use just one ScDocFunc and make it work when (not)collaborating.
Then we can use ScCollaboration directly wiith this ScDocFunc but it
would complicate it a little more.
b, We continue to use more versions of ScDocFunc depending on whether
we collaborate.
But then, I think, we need to use ScCollaboration with ScDocShell, so
it has access to it's ScDocFunc and can change it.

I am not sure what's more ideal.. b, is probably more similar to the
current state but it's messing also with ScDocShell.
a, could be nicer because there would be only one ScDocFunc but that
may not be best.

Thanks to anyone for reading and any comments, questions ...
Matus