Finished ELO rating warmup
Tweak Elo Rating example
Add instructions for saddle point
Add crypto-square warmup
Complete crypto square
Improve crypto example
Add saddle points exercise
Update ideas file and move into proper folder
Simple cipher puzzle.

Starts with Caesar Cipher, extends to substitution ciphers and error correction.
Includes tests, example, readme.
Includes Watchrfile and some instructions.
Still a little concerned that this might be too hard but I'm eager to find out.