Project files were not following the clang-format style. For people
using IDEs were clang-format is always run after a save this would
cause unwanted changes.
This commit only applies "clang-format -i" to files.
* GSL_LIKELY/_UNLIKELY always contextually convert their argument to bool.
* Add macro GSL_ASSUME(cond) to inform the optimizer that the predicate cond must hold.
* Reimplement Expects & Ensures as expressions for flexibility and correctness. (Think about "if (cond1) Expects(cond2); else goto fail;")
* Expects and Ensures GSL_ASSUME their predicate when GSL_UNENFORCED_ON_CONTRACT_VIOLATION is defined.
* Nest "gsl" directory inside a new "include" directory.
* Cleanup the _MSC_VER conditionals a bit; use constexpr on VS2017+.
* Don't #define noexcept on non-Microsoft implementations.
* Workaround VS2017 bug in multi_span. (Also implement == and != for static_bounds_dynamic_range_t because I'm an EoP semantic soundness snob.)
Fixes#441.
