Implement Terminal-Size-Aware Scaling

[zacharygraber]

Is your feature request related to a problem? Please describe.
With current configuration, the game can be small, only occupying roughly 20x20 characters in the terminal.

Describe the solution you'd like
A scale factor should be added to the game that controls how large the rendered squares are from draw_block(...). The game could also intelligently choose the largest possible scale factor (constrained by terminal character width/height) on startup and after any window resize events.

Describe alternatives you've considered
Most terminals worth their salt let you resize text anyway, but having this native would be cool.

[zacharygraber]

Depends on window resize event handling (#4) being completed first.