Patch to automatically select the serial port.

Select serial port which is just connected while a 'Find Arduino' Dialog is
open. You don't have to worry any more when teaching your students to
select the correct serial port.
Automatically "Find Arduino" when uploading

You have to edit the preferences.txt manually to add following line:
  serial.find_arduino_once_each_window=true

With the above setting, "Find Arduino" dialog will apear automatically
when start compiling/uploading first time for each window.

There is a FIXME comment. I tried to prevent the dialog to appear if a
user select a serial port manually. However, I have not yet succeeded
to implement correctly. Hmm...
Japanese translation for the new strings.