This is a pretty straightforward first pass over removing a number of uses of Mutex in favor of std::mutex or std::recursive_mutex. The problem is that there are interfaces which take Mutex::Locker & to lock internal locks. This patch cleans up most of the easy cases. The only non-trivial change is in CommandObjectTarget.cpp where a Mutex::Locker was split into two.
Although the patch is trivial, the question that I have is whether we should go ahead with this change and if doing it in multiple passes is reasonable.