Merge #8353: Trivial: tiny c++11 refactors

c784086 use std::map::emplace() instead of std::map::insert() (whythat)
5e187e7 use c++11 std::unique_ptr instead of boost::shared_ptr (whythat)
947913f use std::map::erase(const_iterator, const_iterator) to get non-constant iterator (whythat)