Improve makeVarlist() and rename

[hrecht]

Deprecate the makeVarlist() function, since list_variables() really provides the necessary info, and then users can filter using dplyr or their own code of choice.

This function was an experiment that never really took off, wasn't really in scope of the package, and I have rarely, if ever, seen anyone use it. It is the only function I plan to deprecate rather than supersede or rename.

[hrecht]

Upon further reflection I think this function that wraps listCensusMetadata actually serves a potentially useful role and should survive in some form. It could be improved though with better parameter names and maybe other tweaks.