Merge pull request #5 from Negusbuk/master

Keithley classes now allow to change the update interval during runtime
Merge pull request #6 from Negusbuk/master

Keithley update interval is now changeable via a combo box
fix in log message writting to XML output file
fix in reading of log messages
added code to dump thermoDAQ log messages to screen
added code to dump thermoDAQ log messages to screen
added code to dump thermoDAQ log messages to screen
removed predefined USB device files
changed USB devices to newly assigned udev ones