3D box: Option for using 'last used style' should be removed or used to assign the side colors in the preferences

Summary:

The 3D box tool has its own set of default colors, defined in a section with the id "3dbox" in the preferences file.

It's possible to set a last used style option in the tool's preferences, but it's not used, and also doesn't make a lot of sense, unless the object it's taken from is a 3D box. In that case, it could assign the side colors to the box, and allow users to customize their boxes more easily.

Steps to reproduce:

• open Inkscape
• set 3D box to use 'last used style'
• draw a bit
• create a 3D box

What happened?

It's default blue.

What should have happened?

Possible solutions:

Option a): (second best) the option to set this shouldn't exist.
Option b): (worst, as the box will then get the same color for all sides) the box should have the style I set
Option c): (best one) there could be an option to 'take default style from selected 3D box'

Version Info:

- Inkscape Version: 1.0.1 (16f50bf4c4, 2020-09-08)
- Operating System: Linux Mint 19.3