cleanup use of boost::function include

[Ichthyostega]

boost::function got included into the TR1 (technical report 1) for the upcoming C++0x standard and thus can be expected to be an important building block of the emerging new standard library.

At places, we still include this header as <boost/functon.hpp> and identify the type as boost::function. We should convert all uses into including <functional> and using std::tr1::function and std::tr1::bind

This is a trivial task for a programmer assustomed with this library, but be warned that you will have to face very wired compiler messages ;-) in getting this to work

[Ichthyostega]

we got increasingly problems with ambiguous or unresolvable placeholders. I could track this down to boost::argument<N> being picked up by ADL, which was due to sometimes using boost::function and sometimes std::tr1::function....

[Ichthyostega]

just to add this information somewhere...

Debian/Lenny is our reference platform; thus for now we rely on boost 1.34 (current is 1.38). The documentation for boost.TR1 states, that the includes should be either <boost/tr1/XXXX.hpp>, or (if you deliberately put INC/boost/tr1 into the include path) it should be <XXXX>. Unfortionately this doesn't work for us, seemingly caused by an bug which is "fixed in current SVN" (yes, we all know how developers feel...).

Surprisingly though, #include <tr1/XXXX> works in the default configuration. I have not the slightest inclination to find out why or what wired mixture of glibc++ and boost we get by this, as long as it works....