PDFUSB python exec remains active when Editra is closed

[GoogleCodeExporter]

What steps will reproduce the problem?
1. don't plug a board, so uploading won't work
2. click "upload", having selected "PDFUSB" bootloader
3. exit from Editra

What is the expected output? What do you see instead?

python process in charge of running UsbBootLoader.py should be killed, as a 
child of Editra parent process. Instead, it keeps running, taking a lot of CPU, 
indefinitely. 

JaluinoIDE should register to some Editra closing event in order to kill every 
processes it could have launched.

Original issue reported on code.google.com by [email protected] on 28 Nov 2010 at 10:33