Upgrades to caesar_cipher.py (#1958)

* Added more flexibility to functions, decreased amount of repeating code

* Added docstrings

* Updated input functions

* Added doctests

* removed test piece of code

* black .

* Updated caesar cipher standard alphabet to fit python 3.8

* Update and rename sleepsort.py to sleep_sort.py

* Or 4

Co-authored-by: Christian Clauss <[email protected]>