added anglebetween to vmathf

src/vmath.h

@@ -120,6 +120,10 @@ Vector vrotatef(Vector a, float t) {
     };
 }
 static inline
+float vanglebetweenf(Vector a, Vector b) {
+    return vdotf(a, b) / (vmagnitudef(a) * vmagnitudef(b));
+}
+static inline
 Vector vprojectf(Vector onto, Vector from) {
     float dot = vdotf(onto, from);
     return vmulff(onto, dot);