Visual Studio 2008 Projects: Update and Overhaul

Update the Visual Studio 2008 projects, and give them a cleanup, by moving
many repeated parts into property sheets.  Similar changes to the Visual
Studio 2005 and 2010 project files will follow in the next few days.

	* MSVC_Net2008/glibmm-version-paths.vsprops:
	* MSVC_Net2008/glibmm-build-defines.vsprops: Add property sheets to
	  group together commonly-used items in the Visual Studio 2008
	  projects, like what is done in GLib.
	* MSVC_Net2008/giomm/giomm.vcproj: Move to MSVC_Net2008, clean up
	  by using the property sheets and adjust the paths accordingly.
	  Also add the sources that are added to the giomm sources.
	  Simplify project names a bit.
	* MSVC_Net2008/gendef/gendef.vcproj:
	* MSVC_Net2008/glibmm/glibmm.vcproj:
	* MSVC_Net2008/examples/compose/compose.vcproj:
	* MSVC_Net2008/examples/dispatcher/dispatcher.vcproj:
	* MSVC_Net2008/examples/dispatcher2/dispatcher2.vcproj:
	* MSVC_Net2008/examples/keyfile/keyfile.vcproj:
	* MSVC_Net2008/examples/markup/markup.vcproj:
	* MSVC_Net2008/examples/options/options.vcproj:
	* MSVC_Net2008/examples/properties/properties.vcproj:
	* MSVC_Net2008/examples/regex/regex.vcproj:
	* MSVC_Net2008/examples/resolver/resolver.vcproj:
	* MSVC_Net2008/examples/thread/thread.vcproj:
	* MSVC_Net2008/tests/glibmm_simple/glibmm_simple.vcproj:
	* MSVC_Net2008/tests/giomm_simple/giomm_simple.vcproj: Move to
	  MSVC_Net2008/, and clean up by using the property sheets.  Update
	  paths accordingly and simplify propject names a bit.
	* MSVC_Net2008/examples/socket-client/socket-client.vcproj:
	* MSVC_Net2008/examples/socket-server/socket-server.vcproj: Move to
	  MSVC_Net2008/, clean up by using the property sheets, and correct
	  the sources that are being built.  Update paths accordingly too,
	  and simplify project names a bit.
	* MSVC_Net2008/examples:
	* MSVC_Net2008/tests: Remove directories as projects have been
	  moved to MSVC_Net2008/.
	* MSVC_Net2008/filelist.am: Reflect on the movement of the project
	  files and also the added property sheets.