"Fewer" button should not remove last copy from build platform

[fiveangle]

Version

1.34.1

Operating system type + version

Mac OS 10.12.4

Behavior

• Fewer command should not remove final remaining model from build platform

When adjusting number of model copies using Fewer button in UI, or Decrease copies menu selection, or ⌘- keyboard shortcut, last model should not be removed.

Delete command already exists for this purpose, so while reducing copies from 1 to none when the last remaining model is on the build platform is technically accurate behavior, it is not expected, especially when the user is quickly hitting the Fewer to remove all copies previously created. Users who accidentially click the button one too many times must reload (and possibly re-orient, re-size, re-position, etc.) wasting time (and increasing frustration ;)

[bubnikv]

Implemented with 0816c99