Creates HERON/data directory to store common HERON data.

[joshua-cogliati-inl]

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Pull Request Description

What issue does this change request address?

Closes #352

What are the significant changes in functionality due to this change request?

Creates a %HERON_DATA% magic word used in src/Placeholders to find HERON/data
Moves shared data from inside tests to HERON/data

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For Change Control Board: Change Request Review

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• 1. Review all computer code.
• 2. If any changes occur to the input syntax, there must be an accompanying change to the user manual and xsd schema. If the input syntax change deprecates existing input files, a conversion script needs to be added (see Conversion Scripts).
• 3. Make sure the Python code and commenting standards are respected (camelBack, etc.) - See on the wiki for details.
• 4. Automated Tests should pass.
• 5. If significant functionality is added, there must be tests added to check this. Tests should cover all possible options. Multiple short tests are preferred over one large tes.
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• 9. If any test used as a basis for documentation examples have been changed, the associated documentation must be reviewed and assured the text matches the example.

[GabrielSoto-INL]

Changes LGTM and add a lot better organization of auxiliary HERON data. As had been previously discussed, added a suggestion for updating the input specs to instruct the user about using the %HERON_DATA% environment variable

[GabrielSoto-INL]

In this file, it might be worth updating the InputData descriptions within the get_input_specs( ) methods of the ARMA(Placeholder) and Function(Placeholder) classes to talk about using %HERON_Data% instead of/in addition to %HERON%. In the modified files, these are lines 169 and 264 respectively (could not find a way to link to them directly in this comment).

[joshua-cogliati-inl]

Okay, I added descriptions of HERON_DATA to those get_input_specs.