Structure_Engine: Geometry3D(Panel) uses VolumePerArea() instead of TotalThickness()

[JosefTaylor]

Description:

Geometry3D is using VolumePerArea() (nee AverageThickness) to extrude panels to a 3D volume, however this is not correct for dimensions and visualization. Instead, it should use TotalThickness() and let the user know this volume should not be used for material takeoff,

Alternately, it could properly extrude the panel property (i.e. ribbed, waffle, etc).

Steps to reproduce:

Expected behaviour:

Test file(s):

[Chrisshort92]

@lborgenstam, this is a good issue to create a branch from to fix the Geometry3D(panel) method.