I removed the Inflector dependency in favor of heck for two reasons:
- to close#3674.
- heck seems simpler and actively maintained
We could probably alter the structure of the `str_` module to expose the
individual casing behaviors better.
I did not feel as confident on changing those signatures.
So I took a lazier approach of a macro in the `mod.rs` that creates the public
shimming function to heck's traits.
* Allow different names for ...rest
* Resolves#3945
* This change requires an explicit name for the rest argument in `WholeStreamCommand`,
which is why there are so many changed files.
* Remove redundant clone
* Add tests
