Fixed some issues, see extended description

Now there's no while loop that was useless, some code lines are been deleted becouse useless, now the pin blinks every 500ms when the read value is below the treshold.
No value changing allowed for user because when no serial is connected no-one could unlock the execution of the program (w8ing for an input would stop any value take-over
Merge pull request #1 from PKangu/master

Fixed some issues, see extended description