[gtkmm/master.nmake] builds: Remove Visual Studio 2017 projects

[Chun-wei Fan <fanchunwei src gnome org>]

commit 78716762a1a45c6b49b047ad0b4eeef46bdeebf1
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Aug 24 18:15:28 2018 +0800

    builds: Remove Visual Studio 2017 projects
    
    Since the NMake Makefiles are now in place, we can remove the project
    files, as they have been superseded.

 MSVC_NMake/gdkmm.vcxproj               | 265 --------------
 MSVC_NMake/gdkmm.vcxproj.filters       |  83 -----
 MSVC_NMake/gendef.vcxproj              | 172 ---------
 MSVC_NMake/gendef.vcxproj.filters      |  20 -
 MSVC_NMake/gtkmm-build-defines.props   |  44 ---
 MSVC_NMake/gtkmm-gen-srcs.props        |  17 -
 MSVC_NMake/gtkmm-install.props         | 521 --------------------------
 MSVC_NMake/gtkmm-version-paths.props   |  78 ----
 MSVC_NMake/gtkmm.sln                   |  65 ----
 MSVC_NMake/gtkmm.vcxproj               | 644 ---------------------------------
 MSVC_NMake/gtkmm.vcxproj.filters       | 453 -----------------------
 MSVC_NMake/gtkmm3-demo.vcxproj         | 254 -------------
 MSVC_NMake/gtkmm3-demo.vcxproj.filters |  57 ---
 MSVC_NMake/install.vcxproj             | 120 ------
 14 files changed, 2793 deletions(-)