Render all objects around center of terminal window.
Allow setting Game grid size.
Use Game grid size to calculate player positions.
Use Game grid size to determine offset for rendering.
Use Game grid size when checking Cycle collisions.
Use Game grid size when stepping Cycle.
Set initial player positions farther out into board.
Merge pull request #32 from carbonfive/feature/center-grid-in-terminal-10

Closes #9 Closes #10