Don't duplicate Catch::isDebuggerActive() check many times, do it just once
in CATCH_BREAK_INTO_DEBUGGER() definition and use a separate CATCH_TRAP()
macro for the really platform-dependent part.
* Empty strings are now direct constructed as `std::string()`, not as empty string literals.
* `startsWith` and `endsWith` no longer construct new a string. This should be an improvement
for libstdc++ when using older standards, as it doesn't use SSO but COW and thus even short
strings are expensive to first create.
* Various places now use char literal instead of string literals containing single char.
** `startsWith` and `endsWith` now also have overload that takes single char.
Generally the performance improvements under VS2015 are small, as going from short string
to char is mostly meaningless because of SSO (Catch doesn't push string handling that hard)
and previous commit removed most string handling if tests pass, which is the expect case.
This fixes the case when we pass signal to previously registered
handler, and it needs to transform the signal into different one.
Still problematic: What if the signal handler we replaced does not
terminate the application? We can end up in a weird state and loop
forever.
Possible solution: Deregister our signal handlers, CALL the previous
signal handler explicitly and if control returns, abort. This would
however complicate our code quite a bit, as we would have to parse the
sigaction we delegate to, decide whether to use signal handler or signal
action, etc...
Only some "signals" are handled under Windows, because Windows does not
use signals per-se and the mechanics are different. For now, we handle
sigsegv, stack overflow, div-by-zero and sigill. We can also
meaningfully
add various floating point errors, but not sigterm and family, because
sigterm is not a structured exception under Windows.
There is also no catch-all, because that would also catch various
debugger-related exceptions, like EXCEPTION_BREAKPOINT.
Also stops Catch from assuming its the only signal user in the binary,
and makes it restore the signal handlers it has replaced. Same goes for
the signal stack.
The signal stack itself probably shouldn't be always reallocated for
fragmentation reasons, but that can be fixed later on.
Now if we detect C++11 compiler, or MSVC in version corresponding to VS2015,
we switch from using `std::random_shuffle` to `std::shuffle`.
`std::random_shuffle` was officially deprecated in C++14, and removed in C++17.
Also removed guarded inclusion of `<random>` header, as there was nothing
in the header that used it.
