Scenery working with children/multiple

"Multiple" is an allowed type now, for when you want Things overlapping
each other (like with scenery!). As a result, there needs to be a buffer
of commands that is sorted before placement.
Added variety to Overworld floors & between

There appears to be a glitch with Floor widths, where they're either 8
or 800. Wat.
Added support for random argument mapping

For macros where "x" and "y" are used for position instead of "left" and
"top", schemas may declare and "argumentMap" to convert attributes such
as "left": "x".