Type hints and type check

Type hints is a modern Python way to provide type information (see typing mypy). PR https://github.com/tarantool/tarantool-python/pull/264 is the first one to potentially use type hints, but it would be nice to have it anywhere.

Type asserts is a more tricky question. For now there are some minor type checks and asserts in connector. Some may also be implemented in PR #264. But it is a big question if they should be use. It seems that there are both adepts of using (since it is a convenient concept) and forbidding to use (since it contradicts Python duck typing principle) it. For example, see this StackOverflow thread. One way or another, it would be good to at least have a consistency on this question.

Since now package is fully documented, it should be easy to implement type hints and asserts after one decide what approach we should stick to. But choosing the approach is the question.

Empieza leyendo PR #264 y las comprobaciones de tipos y asserts existentes de connector; después, revisa la documentación del paquete y las referencias enlazadas sobre typing y mypy. Primero hay que decidir en este issue si se deben añadir anotaciones de tipos y con qué coherencia se usarán las comprobaciones de tipos en tiempo de ejecución o los asserts; se considerará terminado cuando el enfoque acordado se aplique en todo el paquete.