Update dshowhelper to version equivalent to experimental v684 codebase - see http://forum.team-mediaportal.com/threads/mp-1-3-x-dshowhelper-development.113014/#post-921629

This will add DWM queued mode support as an option, plus cleaner frame drop/repeat handling and some other tweaks.

h4. Additional Information
New branch at https://github.com/MediaPortal/MediaPortal-1/commits/FEAT-4357-Update_dshowhelper_to_v684_code