avx2 float3 added added normalize_magnitude added divide fast to float3 may copy to float4 move static spheremesh to drawSphere (initialize on first use) so platform has a chance to load the math backend
mac implementation had _mm_div (x86 intrinsic)
setup libraries for different simd isa's add float4 functions for c sse2 and avx2 (placeholder file for neon to be implemented on mac)