Issue 471 deprecate unused device id methods

[KeynesYouDigIt]

Closes #471

Why is this the best possible solution? Were any other approaches considered?

This adds warnings where other question type specific warnings are. This pattern is modelled after the special validation work used for 'audit' and 'calculate' question types.

I considered checking this information upstream in the survey creation process, but would have to re-divide the sheet into rows. Downstream, during question creation and final survey creation, is another place where warnings can be generated, but we have the information we need at the point where the warnings were added, so no point in working further down.

What are the regression risks?

I did modify constants.py - any modification of a global config represents some regression risk. However, values were only added, and only values that apply to my use case, and only under a name that does not conflict with another name, so I do not see any great risks.

Does this change require updates to documentation? If so, please file an issue here and include the link below.

docs should already be set https://github.com/XLSForm/xlsform.github.io/pull/208/files

Before submitting this PR, please make sure you have:

• [ x ] included test cases for core behavior and edge cases in tests_v1
• [ x ] run nosetests and verified all tests pass
• [ x ] run black pyxform to format code
• [ x ] verified that any code or assets from external sources are properly credited in comments

[lognaturel]

Looking good!

[lognaturel]

Super, thanks so much!!