Add support for input from RECS survey data

[aivanova5]

This PR allows the creation of house models from RECS survey data.

Current issues

1. There is an explicit test of the input file type for census2016, which is not currently being used for anything. The convention is to implement special types of input as separate converters, e.g., json-census2glm.py. This is a minor issue that can be addressed later.

Code changes

• Update gldcore/converters/json2glm.py
• Fix typo is gldcore/load.cpp::property_ref()
• Add global_datadir to python path in gldcore/python_embed.cpp::python_loader_init()
• Change default input filename in gldcore/scripts/gridlabd-plot from None to /dev/stdin
• Add check for missing output filename in gldcore/scripts/gridlabd-plot
• Add python_extras/eia_recs.py

Documentation changes

• Add docs/Tutorials.
• Create tutorials source folder.

Test and Validation Notes

• Update gldcore/autotest/test_library_include.glm

[dchassin]

We should move all the RBSA data to the RBSA project.

[dchassin]

The RBSA data should be stored in the slacgismo/rbsa_data project. Also it should only be stored if it is original data that cannot be sourced otherwise online in an automated manner.

[dchassin]

This converter should produce only the objects that related to the input data, rather than producing a complete GLM. In other words there should be no clock or other objects generated except those the represent the input data. This way users will be able to generate a GLM fragment that can be included in other GLM files as needed.