moving some code around

--HG--
rename : include/munify/unify/vars_binding.hpp => include/munify/unify/variables.hpp
- trying to reduce verbosity and increase readability of the test script
- including a counter to the output of the test script
- including a few more tests
critical bugfix: the tests were all succeeding by mere casualty
introducing atom<>'s that finally work (it seems...)
some more tests and further critical bugfixes