User Guide about CrowdEgress

Welcome to the CrowdEgress wiki! I am drafting a user guide here for CrowdEgress!
Your collaboration is welcome and comments are appreciated!

When pygame screen is displayed, users can use certain keys to adjust the display features:

1. Use pageup/pagedown to zoom in or zoom out the entities in screen
2. Use space key to pause the simulation
3. Use arrows to move the entities vertically or horizonally in screen.