robot-simulator: improve equals for GridPosition

saddle-points: make MatrixCoordinate implement Comparable

* topics added for slug- palindrome- products

* modified topics for slug- palindrome-products

* added topics for robot simulator

* removed algorithms as topic

* Add topics to flatten-array

* Fixed identation to 2 spaces

We recently improved the implementation of equals for GridPosition so
that we could use assertEquals in the tests. However, we only changed
the reference implementation, not the starter implementation. This
changes the starter implementation to be the same as the reference
implementation.

* Added Tournament exercise

* Added to config and refactored after review

* Added topics and fixed indentation

* Must be unlocked by a core exercise

maintainers.json: show bio for Frida Tveit

The saddle-points tests make it seem like you can use any kind of set
for your output. However, if you use TreeSet then the tests will fail
because MatrixCoordinate doesn't implement Comparable.

MatrixCoordinate does now implement Comparable to preent this failure.

meetup: add topics

Renamed classes and added @Before method to test class

changed variable name and made it private

* Adding topics to prime factors

* Adding math as problem area

* Removing recursion as a topic

Add topics to sieve

Add topics to problem 'nth-prime'

Added topics to Matrix exercise. Fixes #852

Added Topics to Collatz Conjecture #870

Added stubs to Matrix #547

complex-numbers: Add topics for exercise to config.json per #873

Add new exercise section to the contributing guide

Added stubs to LargestSeriesProductCalculator

Make changes per review comments

Made class and methods package private

* Completes #853

* Add more topics to problem Kindergarten-garden

* Correct the identation

* Correct the identation again

list-ops: add hint of using static methods per #378

wordy: add topics for exercise to config.json per #850

* added topics to perfect numbers

* updated topics

* fixed tabs

Add topics to sum of multiples exercise

Add topics to Secret Handshake exercise

Add topics to transpose exercise

scrabble-score: add topics

Removed recursion