function getTranslation(m, dst) {
    dst = dst || v3.create();
    dst[0] = m[12];
    dst[1] = m[13];
    dst[2] = m[14];
    return dst;
  }
Returns the translation component of a 4-by-4 matrix as a vector with 3
entries.
@param {module:twgl/m4.Mat4} m The matrix.
@param {Vec3} [dst] vector..
@return {Vec3} The translation component of m.
@memberOf module:twgl/m4