M_PI bugfix for windows users (C99)
M_PI bugfix for windows users (C99)

AndreasFMueller/SeminarDGL,AndreasFMueller/SeminarDGL,Darnor/SeminarDGL,crazycrank/SeminarDGL,El-Mono/SeminarDGL,crazycrank/SeminarDGL,El-Mono/SeminarDGL,Darnor/SeminarDGL