Add pretty colors to the test runner.
Compile the test runner in advance to reduce `make check` time.
Fix formatting in README.md.
I accidentally a word in README.md.
Remove executable bit from sdb.in.
Reference Mono.Posix.dll.
Use Mono.Unix.UnixSignal for handling SIGINT.

As described in BXC #16444 [0], we cannot use managed signal
handlers because managed/native transitions perform all kinds
of signal-unsafe work. So use the Mono.Posix abstraction that
allows us to wait for a signal and then act on it in normal
managed code.

[0] https://bugzilla.xamarin.com/show_bug.cgi?id=16444
Revert "Use Mono.Unix.UnixSignal for handling SIGINT."

This reverts commit 4f7b796482e926bf6156bf460ce7aa510f4ad44e.
Use Mono.Unix.UnixSignal for handling SIGINT, take two.

Like 4f7b796482e926bf6156bf460ce7aa510f4ad44e, but:

* The EnableControlC configuration option still works.
* It's now more clear where the Ctrl-C handlers are set and unset.
* SIGINT is now properly ignored when the signal handler is inactive.
Bump to version 1.2.