Changed time.sleep to thread event wait() method
Progress bar value limited to 0-1
Display text value centered in label
Last successfully opened port is saved
JSON sending methods return number of bytes written. Serial event can now be 'restarted'. Added isConnected() and portNames() methods.
Save last opened port and try to connect to it at launching
Save last opened port an try to open it at launch. Stream config when a port is opened