* functional mac port
* combine common parts of Linux and Darwin implementations
* add unwind support for apple
* insure BACKWARD_HAS_BACKTRACE_SYMBOL is set for BACKWARD_SYSTEM_DARWIN
* fix indentation
* use pthread_self and pthread_main_np
*Read the pc as specified for aarch64 processors.
*Disable division by zero tests, since aarch64 does not trap these and
therefore does not generate SIGFPEs there.
*All other tests succeed.
This is a breaking change.
The printer now offers a color_mode setting: automatic, always, never.
When given a FILE* stream on linux, the automatic mode will retrieve
file descriptor behind it and call isatty().