Fix for incomplete incoming messages from TP (w/out final newline).

[mpaperno]

This Fixes errors/crashes with messages, or sets of messages, that are too large to fit into one socket buffer before data handler is called, resulting in no terminating newline.

For example when sending long action data (eg. base64 image) or in other cases where socket data builds up, eg. when plugin takes a long time to process a message or is paused in a debugger. I've personally observed all 3 scenarios.

Also as a final check this puts a try/catch around the JSON parsing bit, which at least helps track down anything else unexpected that may happen (not that I've seen that).

Also turns out the data parameter of the on(data) handler was already a string. :) I kept it as a string since apparently it's significantly faster to extract parts of strings than Node Buffers. To make up for the possible buffering overhead, at least we get rid of an array allocation.

-Max