MSVC 2008/2010 Projects: Add "Install" Projects

This adds "install" projects for Visual Studio 2008/2010 builds so that the
build results can be copied to a common directory together with the
dependencies, so that testing and packaging will be made easier.

* MSVC_Net2008/pangomm-install.vsprops:
* MSVC_Net2008/install.vcproj:
* MSVC_Net2010/pangomm-install.props:
* MSVC_Net2010/install.vcxproj: Add MSVC projects and property sheets to
  copy build results to a common directory under the root build directory.
* MSVC_Net2008/pangomm.sln:
* MSVC_Net2010/pangomm.sln: Include the "install" project in the build
  process.
* MSVC_Net2008/filelist.am:
* MSVC_Net2010/filelist.am: Include the added projects and property sheets
  in dist.