modules in modules (only possible with c_builtins) are now completable. however it's kind of hackish, I'm using a class instead of a real module, because this is the easiest way for jedi, fixes #126
end_pos issues, fixes #150
re-enable test, probably related to #131
import end_pos calculated differently, fixes #137
also normal imports should return the right user_stmt, similar case than #137