Send 'set' events on setBlock()

voxel-server and voxel-client listen for 'set' events (voxel edits), but I couldn't see anywhere they were sent. This PR sends these 'set' events over the connection on the voxel-engine 'setBlock' event, except when the event is already being processed from a remote voxel edit (to prevent infinite recursion). 

This fixes client/server voxel edits at least in my testing (ref https://github.com/deathcap/voxel-fuel/issues/11, not sure how you handle this in node-warrior?)