Updated Optional with fix for GCC 4.8 on OSX.
Updated Optional with fix for GCC 4.8 on OSX.

Thanks to Stefan Wasilewski for reporting.

DerThorsten/magnum,ashimidashajia/magnum,DerThorsten/magnum,MiUishadow/magnum,MiUishadow/magnum,MiUishadow/magnum,MiUishadow/magnum,ashimidashajia/magnum,ashimidashajia/magnum,ashimidashajia/magnum,DerThorsten/magnum,MiUishadow/magnum,DerThorsten/magnum,MiUishadow/magnum,ashimidashajia/magnum,DerThorsten/magnum