Adds o to this.
Source
void add(Matrix4 o) {
final oStorage = o._m4storage;
_m4storage[0] = _m4storage[0] + oStorage[0];
_m4storage[1] = _m4storage[1] + oStorage[1];
_m4storage[2] = _m4storage[2] + oStorage[2];
_m4storage[3] = _m4storage[3] + oStorage[3];
_m4storage[4] = _m4storage[4] + oStorage[4];
_m4storage[5] = _m4storage[5] + oStorage[5];
_m4storage[6] = _m4storage[6] + oStorage[6];
_m4storage[7] = _m4storage[7] + oStorage[7];
_m4storage[8] = _m4storage[8] + oStorage[8];
_m4storage[9] = _m4storage[9] + oStorage[9];
_m4storage[10] = _m4storage[10] + oStorage[10];
_m4storage[11] = _m4storage[11] + oStorage[11];
_m4storage[12] = _m4storage[12] + oStorage[12];
_m4storage[13] = _m4storage[13] + oStorage[13];
_m4storage[14] = _m4storage[14] + oStorage[14];
_m4storage[15] = _m4storage[15] + oStorage[15];
}