Basic tests on Option<'t>

Create tests for ```Option<'t>```

* [ ] Lexer/Parser
* [ ] Type checker
* [ ] IR
* [ ] IR Interpreter

Example of type definition.

```
type Option<'t> =
     Some of 't
   | None 
```

Example of function for test.

```
let map o f =
   match o with 
  | Some(x) -> Some (f x)
  | None -> None
```