Add music and sounds

[felixmariotto]

It would be nice to have sounds in the game, particularly when two puzzle parts get merged, and when a puzzle is finished.
A background ambient music would be nice too, or light crowd noises with lot of echo like in museums.

Here is where parts are merged :

art-salad/src/puzzles/puzzleManager.js

Lines 172 to 191 in 0ec2d75

	if (
	part.position.distanceTo( oppositePart.position ) < 0.07 &&
	part.quaternion.angleTo( oppositePart.quaternion ) < 0.5
	) {
	// in here we do the actual merging of one part into the passed part.
	for ( let i = oppositePart.children.length - 1 ; i > -1 ; i -- ) {
	const child = oppositePart.children[i];
	part.add( child );
	}
	const isFinished = ( part.children.length === this.pieces.length );
	events.emit( 'parts-assembled', isFinished );
	}

A event should be fired here with the events module, and this event should be listened in a new audio module.

[felixmariotto]

done