SUT models and t-way tests for Flex, Grep, and Make

* TestModel: SUT (System Under Test) models for projects flex, grep, and make.<br><br>.tsl: Test specification files in SIR repository. <br>.sut: Parameters and values without constraints, made from .tsl files.<br>.calot: Input models in Calot[1] format, made from .tsl files. Single and error parameter values are omitted.<br>.ts: exhaustive test cases in SIR repository.<br>.frame: executable test cases in SIR repository.<br><br>* CombCS: t-way test cases.<br><br>1-, 2-, 3-, &amp; 4-way test cases by PICT, ACTS, and Calot, generated using t-way testing tool Calot.<br><br>* For experiments in [2], we translated t-way test cases in CombCS to corresponding (executable) test cases in .frame format (the omitted parameter values are revived), and investigated code coverage of test cases. <br><br>[1] Akihisa Yamada, Armin Biere, Cyrille Artho, Takashi Kitamura, and Eun-Hye Choi, "Greedy Combinatorial Test Case Generation Using Unsatisfiable Cores," In Proc. of 31st IEEE/ACM International Conference on Automated Software Engineering (ASE 2016), pp. 614-624, September 2016.<br><br>[2] Eun-Hye Choi, Osamu Mizuno, and Yifan Hu, "Code Coverage Analysis of Combinatorial Testing," In Proc. of 4th International Workshop on Quantitative Approaches to Software Quality（QUASoQ 2016), in conjunction with APSEC 2016, pp. 34--40 December 2016.<br><br>