Overhaul The Visual Studio 2010 Projects

Give the Visual Studio 2010 Projects an overhaul, by using property sheets
to consolidate commonly-used items, and moving all the projects to
MSVC_Net2010.  Also stop using the /vd2 compile-time option, as it is more
harm than help here, since it causes weird crashes.

	* MSVC_Net2010/pangomm-build-defines.props:
	* MSVC_Net2010/pangomm-version-paths.props: Add property sheet
	  sheets to consolidate commonly-used items items so that projects
	  can refer to them, which will help to simplify future
	  maintenance.
	* MSVC_Net2010/gendef/gendef.vcxproj:
	* MSVC_Net2010/gendef/gendef.vcxproj.filters:
	* MSVC_Net2010/gendef/pangomm.vcxproj:
	* MSVC_Net2010/gendef/pangomm.vcxproj.filters: Move to
	  MSVC_Net2010/, and clean up using the property sheets.  Adjust
	  the source file paths accordingly, and remove the /vd2 compile-
	  time option as it brings more trouble than help.  Add
	  PlatformToolset tags so to ease future move to Visual Studio
	  2012/2013.
	* MSVC_Net2010/filelist.am:
	* MSVC_Net2010/pangomm.sln: Update file paths accordingly.