Better packaging

[ADDED]

• Walktrough demo in README.
• Automatic releases to PyPi.

[FIXED]

• Pymunk was broken due to insufficient version requirement.
• Some typos in README.
• Versioning workflow not executing.

v0.0.2-alpha

Fixed some package problems

This version is essentially a bug-fix a various problems with the Python Package.

Added

• requirement.txt was absent due to .gitignore misconfiguration.

Changed

• .gitignore now ignores *.txt files only in the leggedsnake folder
• environment.yml more flexible (versions can be superior to the selected). pymunk>5.0.0 and pylinkage added.
• leggedsnake/utility.py not having zipfile or xml modules error encapsulation

Fixed

• setup.cfg was not PyPi compatible.
  Removed mail (use GitHub!), and we now explicitly say that README.md is markdown (PyPi is conservative)