Automate number-to-peano conversion.

Automate the conversion of numbers from decimal to peano when passed as parameters to the relations "add" and "multiply".

Example:

``` python
goal = Goal.with_variables(
lambda x, y:
multiply(x, y, peano.to_peano(24)))
```

Will become:

``` python
goal = Goal.with_variables(
lambda x, y:
multiply(x, y, 24))
#24 is automatically converted to peano inside the relation.
```

Look at the `multiply` and `add` relation definitions in the codebase to understand how parameters are currently processed. The goal is to modify these relations to automatically convert integer arguments to Peano representation. Start by examining the `peano.to_peano` function and see where it's called. Then, update the relation logic to handle this conversion internally. Test by creating a goal with a raw integer and verifying it works as the example shows.

Vom Indexierungsmodell aus dem Issue-Text verfasst.