std vector 的消滅

早期使用方式:
for (vector<Vector4*>::iterator it = mPt.begin(); it != mPt.end();) {
Vector4 *pVt = *it;
delete pVt;
it = mPt.erase(it);
}

在大量數據時會很慢，更新為下列方式:

while (!mPt.empty()) {
Vector4 *pVt = mPt.back();
delete pVt;
mPt.pop_back();
}