C++ representation of time duration, time point, and clocks

 This package forms part of the Boost C++ Libraries collection.
 .
 The Boost.Chrono library provides:
 .
  * A means to represent time durations: managed by the generic duration
    class.Examples of time durations include days, minutes, seconds and
    nanoseconds, which can be represented with a fixed number of clock
    ticks per unit. All of these units of time duration are united with
    a generic interface by the duration facility.
  * A type for representing points in time: time_point. A time_point
    represents an epoch plus or minus a duration. The library leaves
    epochs unspecified. A time_point is associated with a clock.
  * Several clocks, some of which may not be available on a particular
    platform: system_clock, steady_clock and high_resolution_clock. A
    clock is a pairing of a time_point and duration, and a function
    which returns a time_point representing now.
 .
 To make the timing facilities more generally useful, Boost.Chrono
 provides a number of clocks that are thin wrappers around the
 operating system's time APIs, thereby allowing the extraction of wall
 clock time, user CPU time, system CPU time spent by the process:
 .
  * process_real_cpu_clock, captures wall clock CPU time spent by the
    current process.
  * process_user_cpu_clock, captures user-CPU time spent by the current
    process.
  * process_system_cpu_clock, captures system-CPU time spent by the
    current process.
  * a tuple-like class process_cpu_clock, that captures real, user-CPU,
    and system-CPU process times together.
  * a thread_clock thread steady clock giving the time spent by the
    current thread (when supported by a platform).
 .
 Lastly, Boost.Chrono includes typeof registration for duration and
 time_point to permit using emulated auto with C++03 compilers.