v2.2.0: Version 2.2.0

* Breaking: Renamed all unprefixed internal macros and functions that were
  exposed in the API, and moved them to criterion/internal.
  This shouldn't break your code if you did not use these in the first
  place.
* Change: Added language-specific wrapping logic to decouple the language
  the tests are written in from the test runner.
* Change: Rewrote the reporting logic to allow multiple test reports to be
  written using any format.
* Addition: Added parallel jobs for the test runner.
* Addition: Added C++ allocator for STL collections based on
  cr_malloc/cr_free.
* Addition: Added criterion::parameters in C++ for simpler parameter list
  generation.
* Addition: Added saner defaults when the tests detect they run under
  valgrind.
* Addition: Added basic Objective-C language support.
* Addition: Added JUnit XML reporting.
* Addition: Added JSON reporting.
* Addition: Added dynamic reporter registration.
* Addition: Added back support for GCC 4.6 when compiling C tests.
* Addition: Added single test execution mode.
* Removal: Removed all deprecated 1.x unprefixed assertion macros.
* Fix: Fixed some memory corruption happening on rare occasions on assert
  messages.
* Fix: Fixed deadlocks happening at random when a large quantity of assert
  is present.
* Fix: Fixed the library not compiling with the intel compiler collection.
* Deprecation: All cr_assume_strings_* macros are deprecated in favor of
  cr_assume_str_*.
* Deprecation: All cr_assume_arrays_* macros are deprecated in favor of
  cr_assume_arr_*.