- remove unnecessary includes
- expunge all remaining usages of boost::format
- able to leave out the expliti string(elm) in output
- drop various operator<<, since we're now picking up
custom string conversions automatically
- delete diagnostics headers, which are now largely superfluous
- use newer helper functions occasionally
I didn't blindly change any usage of <iostream> though;
sometimes, just using the output streams right away
seems adequate.
Actually I arried at the conclusion, that the *receiving* of
a diff representation is actually a typical double-dispatch situation.
This leads to the attempt to come up with a specialised visitor
as standard pattern to handle and apply a diff. Obviously,
we do not want the classical GoF-Visitor, but (yes, we had
that discussion allready) -- well in terms of runtime cost,
we have to deal with at least two indirections anyway;
so now I'm exploring the idea to implement one of these
indirections through a functor object, which at the same time
acts as "Tag" in the diff representation language (instead
of using an enum as tag)
initial considerations; there is a concurrency problem, since
all of session handling within Proc is deliberately not threadsafe.
Thus the decision is to make this the gui::model::SessionFacade's responsibility
