Bugfixes from peer review

Slide 3, changed printing of a variable into two statements.
Slide 5, Fixed code Typo "Servo.h"
 Changes to be committed:
	modified:   code/code_statements/code_statements.ino
	modified:   code/potentiometers-servos/potentiometers-servos.ino
	modified:   code/potentiometers-servos/potentiometers-servos.ino~
	modified:   images/analogue_code.png
	modified:   worksheet.odg
	modified:   worksheet.pdf