TAP-compatible test function

[pocomane]

Some note on the code:

• I changed the one-argument mode to implement the "Tap diagnostic" since Tap have not the concept of "Suite". However, in my previous implementation, Suite was just logging so, you can reproduce it with Tap diagnostic.

• Using taptest to test itself make the example a bit confusing. I tryed as much ad possible to clearify the example. Maybe it is better to write a simplier one?

• The example write another 'ok X' line after ending plan summary. This is not allowed in standard TAP, but for now I can not guess how get rid of it. IIt is just an issue of the example, I hope your CI scripts will accept it.

• For now, no argument type check are performed

• I put it in the sys directory, maybe you have some better solution

[pocomane]

Indeed the CI complains about the line after the ending plan :(

[pocomane]

Sorry for hammering. At the end, I disabled the final faliures count, which I found to be very useful when looking at the test report without an harnesser. However it is still failing due to the test masking trick. :(