Use standard namespace for isinf
Use standard namespace for isinf

This one is in the standard namespace. Otherwise it won't compile on stricter compilers. Contributes to #2.
ROBO3D/CuraEngine,totalretribution/CuraEngine,Ultimaker/CuraEngine,pratikshashroff/pcura,alephobjects/CuraEngine,markwal/CuraEngine,markwal/CuraEngine,pratikshashroff/pcura,markwal/CuraEngine,ROBO3D/CuraEngine,ROBO3D/CuraEngine,pratikshashroff/pcura,totalretribution/CuraEngine,alephobjects/CuraEngine,alephobjects/CuraEngine,Ultimaker/CuraEngine,totalretribution/CuraEngine