New argument/error checking approach, new features, addressing #158, #223, & #262

[jmobrien]

Parents, talk to your children about the dangers of refactoring code.

Okay, so this got into a lot, but it's done now, and I think I really managed to clean things up. Quick list of what's done here:

• All arguments are now handled in a straightforward way with functions in file arguments.R, addressing Proposal: get rid of assertthat and replace with unified argument checking/adapting framework w/rlang #262
  • General purpose functions do common checks (string, boolean, integerish, character w/o missing)
  • More detailed checks for specific arguments also perform formatting as needed
  • All error handling operates using rlang::abort (and similar), using cli-type format
  • argument checking/formatting handled directly at the start of each main function
• Removed:
  • assertions.R (and dependency on assertthat, unless I missed something)
  • check_params(), which was redundant and no longer needed
  • Most of construct_raw_payload(), which no longer does argument formatting and just formats request bodies. This should mean that it's re-usable for other features (e.g., a function for New feature request: Deactivate surveys via API #215)
  • Some old, apparently no longer used code in the main request and response code functions.
• New features:
  • fetch_survey() now fully handles dates & times of Date, POSIX, or equivalent character, closing ideas: setting up more flexible handling of start and end date params #158
    • Updated timezone handling
    • end_date adds 23:59:59 to time when just a date. This avoids the unintuitive situation where specifying end_date = "2020/03/03" would actually only get cases from 03/02 and before
    • default for timezone is now system locale rather than UTC, which means that things like calling `as.character() on the typical formatting of a datetime object will produce the expected results
  • fetch_survey() now has three include_* arguments that allow selection of metadata, questions, and embedded data, closing Feature: Include Embedded Data in Survey Questions #223
  • fetch_survey() now uses a more modular structure for handling the multiple calls involved in a fetch.
  • In updating the arg checking and error reporting in fetch_id(), added partial name matching & more informative error reporting when multiple surveys are matched.
• Updated tests
  • Everything works
  • Did remove one webmockr test from test-qualtrics-api-request.R that didn't seem to work with new format for reasons I couldn't diagnose, but whose functionality seemed to be covered mostly by other tests.

[jmobrien]

One other thing I forgot to mention. In porting over the smart argument checking from #257, it now handles removing the protocol with a message, rather than completely erroring out.

[jmobrien]

Commits
be6e896 through 737f26a are to repair issues with the CMD checks. (Sorry that took a few more than I intended).

If this works for you, I think we can delete assertthat from Imports

[juliasilge]

This is QUITE a lot of work you did here, and what an improvement it will be for the package in the long run!! Thank you 🙌