Use step patterns and macros instead of using plain .feature files

[noname0443]

First step to solve #13

[noname0443]

Now I'm not sure about this PR... I believe we can introduce more capable steps instead of creating weird macros and definitions, because this path can lead us to strange situations where half of test code will be written in .def files, and we should read all definitions before logic of tests, then patterns and compile result in the head to identify bugs, for example.