Add provided BST.hs file
Add solution for Exercise 1
Add solution for Exercise 2
Add solution for Exercise 3
Add solution for Exercise 4
Add solution for Exercise 5
Add solution for Exercise 6
Add solution to Exercise 7
Add solution for Exercise 8
Add solution for Exercise 9
Add solution for Exercise 10
Add solution for Exercise 11
Add solution for Exercise 12
Add solution for Exercise 13
Add provided functions for remaining exercises
Add solution for Exercise 14
Add solution to Exercise 15
Add solution to Exercise 16
Add solution to Exercise 17
Merge branch 'hw04'