made similar to glibmm, with the gendef program

        * .gitignore: added gendef's automatically generated project files
        * MSVC_2010/gendef/gendef.cc:
        * MSVC_2010/gendef/gendef.vcxproj:
        * MSVC_2010/gendef/gendef.vcxproj.filters: symbols generator added
          (just like in gtkmm project)
        * MSVC_2010/gstreamermm.sln: added gendef's project to a main
          solution
        * MSVC_2010/gstreamermm/gstreamermm.vcxproj: switched build to
          dynamic library, ran gendef program before build