glib-genmarshal is now a Python script instead of a compiled program, so
we need to:
-Remove the projects that are used to build the glib-genmarshal sources.
-Generate the full glib-genmarshal Python script from glib-genmarshal.in
-Make Python a hard build-time requirement, since we use this tool
in many parts of the stack (and it is the case for glib-mkenums).
-Tell people in the Visual Studio build README.txt files that Python
2.7.x or 3.x is now required for the build/"install".
This adds support for Visual Studio 2017 by updating the autotools files for
copying and updating the Visual Studio 2010 project files.
Since the toolset version of Visual Studio 2017 is no longer in the form
of $(MSVC_VER_SHORT)0, we need to specify the full number, but this is a
rather simple change we have here. Note that Visual Studio 2017's CRT
aims to be compatible with the 2015's CRT, so it should be possible to
use 2017-compiled code with the 2015-compiled ones.
