Limit instructions per second (#50)

* Add tick counter for execution speed control

* Update README table of contents

Fix right shift bit one bug. (#49)

Update README.md

Merge pull request #22 from craigthomas/pre-v2-updates

Compatibility Update

Merge pull request #18 from electricalgorithm/pygame_init

added pygame.init() / Program couldn't run before

Merge pull request #17 from craigthomas/python-36-upgrade

Python 36 Upgrade

Merge pull request #15 from craigthomas/coverage-fixes

Updated Travis requirements and Unit Tests