Slightly better readability.

I've enhanced triplets to quadruplets, fourth item is assertion message.
By default it's OK message "just a simple addition, shouldn't be
faulty".

When test input data are somewhat tricky, it's now possible to mark such
input with it's own assertion message.

Now one interesting finding: I've made an error while doing this.
While I did add message declaration, and while I changed assertion to
one with message, I forgot to add

	this.message = msg;
and add one more param to test constructor.

Result was strange, and it took me a few minutes to realize what was
wrong.

Minuses of this solution: IDE backup becomes unreliable. IDE cannot
pinpoint where the problem is, stacktrace is off, test naming is lost,
as each test becomes test[index] and there's no way you will remember
which index corresponds to which input data set.