Solved Day13. Used mutable classes & got bitt...

# advent-of-code

[andyb]

Solved Day13. Used mutable classes & got bitten by it as input for Part 2 had already been mutated by Part 1.
Solution is here but don't think there's anything too sophisticated: https://gitlab.com/abowes/adventofcode2018/blob/master/src/main/kotlin/jfactory/day13/Day13.kt