More dynmaic linking options

This adds the following options to the `configure` program

  --shared-v8           Link to a shared V8 DLL instead of static linking
  --shared-v8-includes=SHARED_V8_INCLUDES
                        Directory containing V8 header files
  --shared-v8-libpath=SHARED_V8_LIBPATH
                        A directory to search for the shared V8 DLL
  --shared-cares        Link to a shared C-Ares DLL instead of static linking
  --shared-cares-includes=SHARED_CARES_INCLUDES
                        Directory containing C-Ares header files
  --shared-cares-libpath=SHARED_CARES_LIBPATH
                        A directory to search for the shared C-Ares DLL
  --shared-libev        Link to a shared libev DLL instead of static linking
  --shared-libev-includes=SHARED_LIBEV_INCLUDES
                        Directory containing libev header files
  --shared-libev-libpath=SHARED_LIBEV_LIBPATH
                        A directory to search for the shared libev DLL

and removes --system.