There are some cases where you need to have an argument to have an
alias, an example could be when you depricate one option in favor of
another one.
Now you are going to be able to alias arguments as follows:
```
Arg::with_name("opt")
.long("opt")
.short("o")
.takes_value(true)
.alias("invisible")
.visible_alias("visible")
```
Closes#669
* feat: adds App::with_defaults to automatically use crate_authors! and crate_version! macros
One can now use
```rust
let a = App::with_defaults("My Program");
// same as
let a2 = App::new("My Program")
.version(crate_version!())
.author(crate_authors!());
```
Closes#600
* imp(YAML Errors): vastly improves error messages when using YAML
When errors are made while developing, the panic error messages have
been improved instead of relying on the default panic message which is
extremely unhelpful.
Closes#574
* imp(Completions): uses standard conventions for bash completion files, namely '{bin}.bash-completion'
Closes#567
* imp(Help): automatically moves help text to the next line and wraps when term width is determined to be too small, or help text is too long
Now `clap` will check if it should automatically place long help
messages on the next line after the flag/option. This is determined by
checking to see if the space taken by flag/option plus spaces and values
doesn't leave enough room for the entirety of the help message, with the
single exception of of if the flag/option/spaces/values is less than 25%
of the width.
Closes#597
* tests: updates help tests to new forced new line rules
* fix(Groups): fixes some usage strings that contain both args in groups and ones that conflict with each other
Args that conflict *and* are in a group will now only display in the
group and not in the usage string itself.
Closes#616
* chore: updates dep graph
Closes#633
* chore: clippy run
* style: changes debug header to match other Rust projects
* chore: increase version
