Updated iterators
Updated iterators

* Use const auto & instead of auto &&
* Use const auto & instead of for(size_t pos = 0; pos < ....)


Former-commit-id: 9b3c07952c0b35db42976393f490da20e1739a0a
DavidAce/DMRG,DavidAce/DMRG,DavidAce/DMRG,DavidAce/DMRG