Differentiate Enemies By Size

Enemies now bin into four size classes depending on power.
Put Power Level Badge on Monsters

Adds a display of a monster's power level to its graphic.
Increase Player Power

The player's power goes up after colliding with a monster of lesser
power.
Provide More Interesting Monster Spawn Power

Monster power should now reflect the player's power, so that the player
isn't inundated with powerful or weak enemies.

This is still probably not the final spawning behavior, but it will do
for now.
Vary Monster Speed by Power

Zeroes are immobile. Weak monsters are slower. Powerful monsters are
faster. One-hundreds are ponderous.
Remove Extraneous Blank Line