If a lock is used with a mutex that doesn't need to be unlocked again before the lock is destroyed, std::lock_guard can be more efficient than std::unique_lock due to less overhead.
This commit also removes a redundant set of curly braces in PIDController.cpp intended to constrain a lock's scope.
Change-Id: Idd692ce439528ddb319a4c62c40c7351a664eb97
Because we want to be able to compile/run wpilibC++Sim on
windows, we would prefer not to require a windows version
of pthread. This commit moves from pthread constructs to
standard library constructs.
Change-Id: I12392a8910189537dd067afdf017e4994d570a66
