Port.send() should not continue to send a packet if an error occurs when it is encoded

[colinbdclark]

Right now, if a Port encounters an error during the process of sending an OSC packet—for example, if it fails to encode the packet due to errors in its structure—it will continue to attempt to send the message, causing unhelpful exceptions to be thrown.

Instead, osc.js should fire the error event and discontinue its efforts to send the packet. Arguably, if no error event handler is registered, it should do something more drastic such as logging a message or throwing an Error, since without this, the system would fail silently and with the appearance of success.

[colinbdclark]

Relates to #73, and the semantic for errors at both layers of osc.js is described in more depth in #72.