[plt-scheme] C++ Bindings using FFI

Ok, so how should we summarize this discussion?

First of all, I see a lot of arguments for using the FFI to create
scheme/C bindings.

However, without CASE functionality that SWIG provides it
still looks like a hell of a job to bind e.g. all 12.000 functions
and #defines, enumeration types, of Gtk+ 2.x

 From the typemaps I provided to SWIG at this moment almost
155.000 lines of C binding code are generated.  I need only
about 6.200 lines of C code to do other administration things.
That makes only 4% of the C code hand coded. With every
gtk header file I add, this percentage is decreasing.

--Hans