fn runner() and fn from_cli(cli: Cli) util functions are located to
app.rs. However, those are utils for runner. So this commit change the
functions to runner.rs.
Use `-C` / `--extra-config` to load Lua files to overwrite the default
or user defined config.
This helps with integration, where integrating xplr with another tool
requires xplr to overwrite some config, without requiring the users to
install an xplr plugin or update the xplr config.
Example:
```bash
xplr -C one.lua two.lua
# Or
xplr -C one.lua -C two.lua
```
> **WARNING:**
>
> Extra config doesn't require specifying the `version`, hence, it's the
> integration author or the user's responsibility to assert
> compatibility using the globally exposed `version` in the extra config
> files, similar to xplr plugins.
Ref: https://github.com/sayanarijit/xplr/issues/316
This improves the compatibility and adds the ability to introduce
non-breaking changes by using a builder pattern.
Example:
```rust
fn main() {
match xplr::runner(None).and_then(|a| a.run()) {
Ok(Some(out)) => print!("{}", out),
Ok(None) => {}
Err(err) => {
if !err.to_string().is_empty() {
eprintln!("error: {}", err);
};
std::process::exit(1);
}
}
}
```
Shunsuke Mie
Arijit Basu
Tom van Dijk