[0.1.dev23] automatically add interaction term table indices to list of columns r…

[mxndrwgrdnr]

…equired to generate merged choice table object.

The only tricky thing about this PR is that it requires the indices of a multi-indexed table of interaction terms to have the indices ordered, with the index corresponding to the observations table as the outermost or first index, and the the index corresponding the the alternatives table is the second or innermost index. I have updated the docstrings accordingly in the large_multinomial_logit.run() method, and also in the choicemodels.tools.mergedchoicetable constructor in a PR here.

[coveralls]

Pull Request Test Coverage Report for Build 98

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 6 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 89.709%

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Files with Coverage Reduction	New Missed Lines	%
/home/travis/build/UDST/urbansim_templates/urbansim_templates/models/large_multinomial_logit.py	6	94.02%

Totals
Change from base Build 91:	-0.1%
Covered Lines:	985
Relevant Lines:	1098

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💛 - Coveralls

[smmaurer]

Looks great