Handle fail messages

[segabor]

SuperCollider returns /fail message when it fails to process received message.

[segabor@csihuhu OSCCore]$ swift run SuperColliderExample
[message] Address: /fail; Arguments: [/s_new, SynthDef not found]
[message] Address: /fail; Arguments: [/n_set, Node 4 not found]
[message] Address: /fail; Arguments: [/n_set, Node 4 not found]
[message] Address: /fail; Arguments: [/s_get, Node 4 not found]

Let's extend SCClient to handle them.