Making some exercises optional
To avoid name collisions
Working on lab 1
Working on OO, Exercise 1
Working on Exercise 3.
Working on OO, Exercise 1
Fixing conflict.
Working on exercise 4
Merge branch 'master' of github.com:bwiedermann/scala-labs

* 'master' of github.com:bwiedermann/scala-labs:
  Working on Exercise 3.
  Working on OO, Exercise 1
  Working on lab 1
  To avoid name collisions
  Working on Exercise 3.
  Working on OO, Exercise 1
  Working on lab 1
  To avoid name collisions
  Working on OO, Exercise 1
  Working on lab 1
  To avoid name collisions
  To avoid name collisions

Conflicts:
	labs/src/main/scala/org/scalalabs/basic/lab01/OOExercise.scala