More fields on the sample object

[peterfpeterson]

This issue was originally TRAC 8012

This is to add the fields to the Material and to the algorithm SetSampleMaterial.

• In SetSampleMaterial, add a field for the mass density which will convert the value to a number density if sample composition is known, and generate an exception if there isn't a composition
• Add a field for the packing fraction. This has valid values 0<frac<=1.
• Add a field for the mass
• Number density = mass density *6.022e23 / Total atomic mass (when mass density is in g/cm^3)

[peterfpeterson]

@NickDraper (2014-02-02T15:34:49):
Moved to backlog at the end of Release 3.1

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@NickDraper (2014-02-14T11:05:00):
Bulk move to assigned at the introduction of the triage step

[peterfpeterson]

Modified based on the current state of the repository and a found equation

[peterfpeterson]

The new version of this is #25389