Query:
- Change semantics of operator in:
  - no-longer greedy
  - now takes a single Array literal parameter
  - allows to test Arrays from tested value
  - accepts an Array of searched values, returning the lowest position of found values, false if one value is not found
- Operator 'contains' has the same semantic of in but container is it's left operand instead of right for "in'
- Implement 'in' and 'contains' operator using internal contains() function.
- Add 7 tests
- Update documentation