This patch:
* Removes the `ArgSettings::Global` variant, and replaces all
users of it to `Arg::global(...)`. The variant itself is lifted up
into a field on Arg. This was deprecated in clap 2.32.0.
* Removes AppFlags::PropagateGlobalValuesDown. This was deprecated in
clap 2.27.0.
* Removes `Arg::empty_values`. This was deprecated in clap 2.30.0.
* Removes `ArgMatches::usage`. This was deprecated in clap 2.32.0.
Tons of code has been moved into functions, deduplicated, made much
easier to read, maintain, and understand. Comments still need to be
added, but that will happen shortly. Modules have also been moved around
to follow Rust conventions and best practices.
All functionality remains exactly the same