Enable calling Notepad++ from octave window

edit file named octaverc located in:
c:\software\octave-3.6.4\share\octave\site\m\startup\octaverc

It should look like this:

## System-wide startup file for Octave.
##
## This file should contain any commands that should be executed each
## time Octave starts for every user at this site.
edit editor "C:\\Program Files (x86)\\Notepad++\\notepad++.exe %s";
edit mode async;