In the old version requesting the config-value of an option
was a little bit tricky.
Let's say we want to have a plugin which uses a default
port of 1234.
```rust
let value = plugin.option("plugin-port");
match value {
Some(Value::Integer(_)) => {},
Some(Value::String(_)) => {}, // Can never happen
Some(Value::Boolean(_)) => {}, // Can never happen
None => {}, // Can never happen
}
```
Many users of the `cln_plugin` crate are overly cautious
and handle all these error scenario's. Which is completely unneeded.
Core Lightning will complain if you put a `String` where an `Integer` is
expected and will never send the value to the plug-in.
This change makes the API much more ergonomical and actually motivates
some of the changes in previous commits.
```
const MY_OPTION : ConfigOption<i64> = ConfigOption::new_i64_with_default(
"plugin-port',
1235,
"Description");
let value : Result<i64> = plugin.option(MY_OPTION);
```
The result will provide a proper error-message.
It is also safe to `unwrap` the result because it will
only be triggered if the user neglected to provide the
option to the `Builder`.
74d13bb334