Day 6: Complete P31 to P35

Signed-off-by: Pang Yan Han <pangyanhan@gmail.com>
Track auxClasses.scala

This contains the aux package, which contains the OutOfBoundsException
class. It should have been tracked way back but I forgot to do it, so here goes.

Signed-off-by: Pang Yan Han <pangyanhan@gmail.com>