Fixed function commands

[LPGhatguy]

I've been considering starting a tool that operates like a fixed-function version of Remodel. Instead, I think a better idea is to expand the scope of Remodel slightly to have those operations included within it.

remodel script.lua will become remodel run script.lua to free up this namespace, and then new commands can be added like remodel convert, remodel slice, remodel combine, or whatever.