PE2 -- Using CS2030S FP Library APIs

1. This is not an official CS2030S teaching team exercise, there could be bugs / major spelling error. If there's any bug / question is not understandable / complainsss, please tele @yikleong AND not ed
2. Please read the instruction clearly in Question.md. You should not use any other APIs other than what you implemented in Programming Exercises
3. No need checkstyle cuz i created without checking style anyways. (but for your PA2 please check before submit)
4. Solutions are available in Solution folder, but please attempt the question yourself first before looking at the solution.
5. Any feedback or questions is welcome, please tele @yikleong