Back to nickel

OK, this time it does the exactly same procedure used by tshrering on his scripts (on .kobo/kbmenu/onstart/startreader.sh) to start nickel, but first kill nickel (as in .kobo/kbmenu/onstart/killnickel.sh) and runs koreader until exit :) 

I hope this works.
Thanks for all your tests but it is sufficient if you start the script from shell (through ssh) while nickel is running (even if nickel is started from start menu)