changed OSX req to 10.11 and Xcode 7.3 to Xcode >= 7.3
changed OSX req to 10.11 and Xcode 7.3 to Xcode >= 7.3

opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core