Better Building With Better Error Messages (and maybe previews)

## Describe your suggestion
More useful errors when the build command fails instead of "unable to do it", for example, saying if there is not enough height available, or a list of missing blocks for the schematic

And a simple form of size preview, possibly in the form of a 2D bounding box to show the footprint of the schematic

## Settings
An X and Z bounding box (Y wouldn't be needed if my height error suggestion was implemented) that can be enabled/disabled via a "buildfootprint" command (better setting name pending)

## Context
To assist in placement of schematics using the build command