Visual Studio Builds: Add "install" project

This adds an install project to the Visual Studio 2008 and 2010 projects,
which is used to install the built .dll and .lib, along with the headers
needed for glibmm and giomm, to make it easier to deploy amd use after
compilation.

	* MSVC_Net2008/glibmm-install.vsprops:
	* MSVC_Net2010/glibmm-install.props: New property sheets to
	  "install" built DLLs, LIBs and headers.
	* MSVC_Net2008/install.vcproj:
	* MSVC_Net2010/install.vcxproj: New projects to carry out the
	  "installation" process.
	* MSVC_Net2008/glibmm.sln:
	* MSVC_Net2010/glibmm.sln: Build the new install project
	* MSVC_Net2008/filelist.am:
	* MSVC_Net2010/filelist.am: Add the newly-added files for
	  distribution