Change and_ and or_ to use & and | instead of * and + operators

[MaxGhenis]

Currently, and_ and or_ are aliases for add_ and multiply_, respectively (or vice versa, they're duplicative). add_ and multiply_ apply + and * operators, respectively. I'd suggest that and_ and or_ instead apply & and | operators, respectively.

This won't change the result: np.array(bool) * np.array(bool) = np.array(bool), for example. But it would be more explicit, and could improve performance.

Relevant code:

openfisca-tools/openfisca_tools/model_api.py

Lines 75 to 77 in e2bc593

	agg_func = dict(
	add=lambda x, y: x + y, multiply=lambda x, y: x * y, max=max_, min=min_
	)[agg_func]