By setting printing to false and not restarting the sender thread when the print_thread exits in the disconnect method this should allow printcore to disconnect even if the print thread is running.

In particular this makes it possible to ctrl+c out of prontserve durring an m109 where it previously errored out and hung with the following error:

Can't read from printer (disconnected?) (SerialException): device reports readiness to read but returned no data (device disconnected?)

Exiting with an error when prontserve fails to connect on startup. Exiting properly if ctrl+c is pressed durring prontserve startup.

Overriding confirm in prontserve so that it doesn't become unresponsive. It doesn't prompt the user like pronsole but it at least functions.

Preventing Prontserve's temperature polling from sending a new request until a response is received for the previous request.

Added printing flag to get_jobs command list

Removing the static name from pronserve's dns-sd records that was causing naming conflicts on multi-printer networks.

This probably requires using an Unicode-based wx.