Use msgpack::type::FLOAT instead of msgpack::type::DOUBLE.
Use msgpack::type::FLOAT instead of msgpack::type::DOUBLE.

The DOUBLE type has been deprecated; see
https://github.com/msgpack/msgpack-c/wiki/cpp_configure

This addresses https://github.com/tavendo/AutobahnCpp/issues/30

alanpich/AutobahnCpp,stopthatcow/AutobahnCpp,alanpich/AutobahnCpp,stopthatcow/AutobahnCpp,e12009/AutobahnCpp,tempbottle/AutobahnCpp,jpetso/AutobahnCpp,tavendo/AutobahnCpp,shuyunqi/AutobahnCpp,e12009/AutobahnCpp,jpetso/AutobahnCpp,tempbottle/AutobahnCpp,shuyunqi/AutobahnCpp,tavendo/AutobahnCpp,alanpich/AutobahnCpp,jpetso/AutobahnCpp