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
Handle non-ascii names / options in from_usage().
Closes#664 and should make it faster too.
Why aren't the stop_at functions written like `c != a && c != b`?
This should also speeds up the parser (except maybe for short options).
Multi-codepoint characters still can't be used as short options, but people shouldn't non-ASCII options nyway.
Closes#664
Now if one wishes to use value delimiters, they must explicitly set `Arg::use_delimiter(true)` or
`Arg::require_delimiter(true)`. No other methods implicitly set this value.
Closes#666
Previously one could only hide the possible values of an argument application or command wide, and
not on a per argument basis. Now one can use the `Arg::hide_possible_values(bool)` method to hide
only that arguments possible values.
Closes#640
Prior to this change, values were always delimited by default. This was causing issues with code
where the arg had a single value, and contained valid commas and shouldn't be delimited. This
commit changes the rules slightly so that values are not delimited by default, *unless* one of the
methods which implies multiple values was used (max_values, value_names, etc.).
This means single value args should *not* be delimited by default. If one wishes to use the old
way, they can add `Arg::use_delimiter(true)` to such code.
Closes#655
Prior to this commit, clap would mangle help messages with hard newlines
(see #617). After this commit, clap will ignore hard newlines and treat
them like an inserted newline, properly wrapping and aligning text and
then restarting it's count until the next newline should be inserted.
This commit also removes the need for using `{n}` to insert a newline in
help text, now the traditional `\n` can be used. For backwards
compatibility, the `{n}` still works.
Closes#617
