This ports our example testing over to [trycmd](https://docs.rs/) so
we can:
- More thoroughly test our examples
- Provide always-up-to-date example usage
The old way of testing automatically picked up examples. This new way
requires we have a `.md` file that uses the example in some way.
Notes:
- Moved overall example description to the `.md` file
- I added cross-linking between related examples
- `14_groups` had a redundant paragraph (twice talked about "one and
only one"
Since usage parser and yaml are on the way to being deprecated (#8, #9),
doing a rename also seems excessive, so rolling it back.
Past relevant PRs:
- clap-rs/clap#1157
- clap-rs/clap#1257
This better models what users should be doing and makes it so all
comments are more clear. In a prior commit, when a changed an `exit` to
`unwrap`, I disliked the fact that I was mixing an unwrap explanatory
comment in with another comment. This makes them stand apart.
* feat(arg_value): ArgValue can be used for possible_values
Through the ArgValue it is possible:
* `hide` possible_values from showing in completion, help and validation
* add `about` to possible_values in completion
* Resolved a few change-requests by epage
* make clippy happy
* add ArgValue::get_visible_value
* remove verbose destructering
* rename ArgValue::get_hidden to ArgValue::is_hidden
* add test for help output of hidden ArgValues
* Documentation for ArgValue
There is an issue that required to implement From<&ArgValue> for
ArgValue. We should probably find a solution without that.
* fix requested changes by epage
* fix formatting
* add deref in possible_values call to remove From<&&str>
* make clippy happy
* use copied() instad of map(|v|*v)
* Finishing up for merge, hopefully
* changes requested by pksunkara
