message: Use range-for loop when writing mine vein data
  Now that we no longer need the index, a range-for loop is easier.
diff: @@ -305,10 +305,8 @@ NAS2D::Xml::XmlElement* Mine::serialize(NAS2D::Point<int> location)
  }}
  );
  - for (std::size_t i = 0; i < mVeins.size(); ++i)
  + for (const auto& mineVein : mVeins)
  {
  - const MineVein& mineVein = mVeins[i];
  -
  element->linkEndChild(NAS2D::dictionaryToAttributes(
  "vein",
  {{
  