Fixing connection issue between MPLAB X and PICkit3

If you get connection error when using MPLAB X (probably only on Linux) with Pickit 3, follow this order:

1. Power off your target board and disconnect Pickit3 from both your laptop and the target board.
2. Connect PICkit3 with your computer.
3. Connect PICkit3 with your target board. 
4. Power up the target board.