Add test for Slang::Tuxic

FROGGS++

$ git clone https://github.com/FROGGS/p6-Slang-Tuxic p6-Slang-Tuxic-git
$ panda install p6-Slang-Tuxic-git

17:49 <FROGGS> [Tux]: creating a slang that inherits from the Perl 6 grammar is not easily doable as of today
17:50  <[Tux]> I want it yesterday, but next week will be good enough :}

20:50 <FROGGS> [Tux]: how would you call such a slang... say, in case I just made one up

21:04 <FROGGS> https://github.com/FROGGS/p6-Slang-Tuxic