Update requirements.txt and add working custom env code (from README)#2

Open

elliottower wants to merge 3 commits intofrankilepro:masterfrom

elliottower:master

Commits on Feb 11, 2023

Added working requirements.txt, play_custom.py file with example of custom defined game settings (from README)
elliottower
committed
Relaxed requirements.txt to only include hard coded versions for opencv-python, tensorflow, gym (all which resulted in errors/were unable to install with newest version)
elliottower
committed
Put custom env import to end of __init__ import statement to be nondestructive compared to original file, updated custom env settings to match README
elliottower
committed