Simplify usage by supporting new default loop

[clue]

This changeset simplifies usage by supporting the new default loop.

// old (still supported)$factory = newClue\React\SQLite\Factory($loop);
// new (using default loop)$factory = newClue\React\SQLite\Factory();

Builds on top of reactphp/event-loop#226, reactphp/event-loop#229 and reactphp/event-loop#232