Previously, every call to updateSizes() would update every entity. Now, entities
can be marked as dirty, and updateSizes can be called such that it only affects
dirty entities. I changed a few calls to updateSizes to take advantage of this,
but others can probably be optimized too

By default, the world was set to be 1.1 times as tall as the max height
(or the mean). Now, it can be set to an arbitrary factor.

Automatic fitting will still move stuff around horizontally.

Includes a demo scene, some of the military-themed macros, and then selections
of entities of varying sizes