-Reinstate build/win32/vs10/gtk+.sln with the correct EOL (DOS/Windows), so
that it will be correctly recognized by Windows instead of having the
annoying "Unrecognized Visual Studio Version".
-Update property sheets to reflect on new headers added
-Change the demo program to be gtk3-demo.exe, to be consistent with the
names on other platforms, and updated/renamed related project/solution
files, and added overlay.c to the list of demo sources.
