Tidy
shared_state supports more mutex types
clang v503 can't use disable_if on just one of the methods within an instantiated class.
Disable verify_execution in "release" as it incurs an extra overhead
shared_state Tidy
shared_state mutex types
Tidy VerifyExecutionTime
Timer timings
rebuild performance evaluation
shared_state_mutex.h for special mutexes.
shared_state_details doesn't copy by rather inherit shared_state_traits. Which means that as shared_state_traits is instantiated the client can do more when critical sections are created.
Rewrote the usage guide.
shared_state doesn't use volatile any more
shared_state*.h are standalone with C++11. w/o boost

Previously required both the backtrace library and the boost header library.
Backtrace runs faster without xcrun
demangle is better at demangling the exception type than boost::diagnostic_information
Tidy shared_state_traits_helper
Tidy usage description of file shared_state.h
Define SHARED_STATE_NO_TIMEOUT to disable timeouts altogether, all lock attempts will then block indefinitely until the lock becomes available.
The spinning_barrier class should provide a lock-free spinning barrier efficient when the number of threads are fewer than the number of available cores.
Print to stderr when trace_perf fails a test