Adds a setting for both `AppSettings` and an `Arg` method which allows
placing the help text for a particular argument (or all arguments via
the `AppSettings`) on the line after the argument itself and indented
once.
This is useful for when a single argument may have a very long
invocation flag, or many value names which throws off the alignment of
al other arguments. On a small terminal this can be terrible. Placing
the text on the line below the argument solves this issue. This is also
how many of the GNU utilities display their help strings for individual
arguments.
The final caes where this can be hepful is if the argument has a very
long or detailed and complex help string that will span multiple lines.
It can be visually more appealing and easier to read when those lines
don't wrap as frequently since there is more space on the next line.
Closes#427
External subcommands are now supported via the following:
```rust
extern crate clap;
use clap::{App, AppSettings};
fn main() {
// Assume there is a third party subcommand named myprog-subcmd
let m = App::new("myprog")
.setting(AppSettings::AllowExternalSubcommands)
.get_matches_from(vec![
"myprog", "subcmd", "--option", "value", "-fff", "--flag"
]);
// All trailing arguments will be stored under the subcommands sub-matches under a
// value of their runtime name (in this case "subcmd")
match m.subcommand() {
(external, Some(ext_m)) => {
let ext_args: Vec<&str> = ext_m.values_of(external).unwrap().collect();
assert_eq!(ext_args ,["--option", "value", "-fff", "--flag"]);
},
_ => unreachable!()
}
}
```
Closes#372
By using AppSettings::AllowLeadingHyphen values starting with a
leading hyphen (such as a negative number) are supported. This
setting should be used with caution as it silences certain
circumstances which would otherwise be an error (like forgetting
a value to an option argument).
Closes#385
