More updates to FirmataUI

Changed callback order in libfirmata.c, added
progressbar creation/update via callbacks.
firmata init timeout

Currently not handled by FirmataUI, just shell.
Other minor changes.
Created Errno wrapper.

Was having some issues with wxWidgets raising
errno on things that we're serial/connection
thus confusing my checks for firmata problems.

The solution was to have an `int` in libfirmata
that held only connection based errno values.
reset error on close()