tests: Introduce custom test driver.

Basically !427 (closed), but in the form of a custom test driver script.

If I am not mistaken, for the driver script to run properly it is necessary to run "autoreconf" in the source directory and call the configure script again in the build directory.

The output when running tests would be the same we currently have except for tests that don't PASS, in that case, detailed information for each failing line will appear. Make a failing test to try it!