clone function
Creates a new vec4 initialized with values from an existing vector
@param {ReadonlyVec4} a vector to clone @returns {vec4} a new 4D vector
Implementation
List<double> clone(a) {
final out = <double>[];
out[0] = a[0];
out[1] = a[1];
out[2] = a[2];
out[3] = a[3];
return out;
}