Proper, portable exception handling with backtracing in C++11

See GPMueller/trace for a proper exception backtracing library.

This MWE shows how std::nested_exception and std::throw_with_nested can be applied in order to not lose information while propagating
an original std::exception upwards through a chain of function calls and create a backtrace without any overhead (compare e.g. logging of debug messages).
This avoids much of the need for any debugging and provides a way of ensuring that a library does not crash ungracefully.
Output should look something like this:

Library API: Exception caught in function 'api_function'
Backtrace:
~/Git/mwe-cpp-exception/src/detail/Library.cpp:17 : library_function failed
~/Git/mwe-cpp-exception/src/detail/Library.cpp:13 : could not open file "nonexistent.txt"

The example may seem a bit overkill, displaying a library with an API layer, but it shows a thorough way of dealing cleanly with exceptions.
main calls an API function, which in turn calls a library function which deliberately throws. The API function catches the exception and
calls a handler function.

Inspiration for this MWE was taken from https://stackoverflow.com/a/37227893/4069571 and https://stackoverflow.com/a/348862/4069571

Build

CMake is used to configure the build. To build the executable:

mkdir -p build
cd build
cmake ..
cmake --build .

TODO

• Extend this MWE with example exceptions which do not require the code to terminate.
• Create unit tests with catch, using e.g. REQUIRE_THROWS