Enhancement: Make self mutable in config::Override<xxxConfig>.override_config()

[JRAndreassen]

First, great framework...

One question.
Is it possible to make the self parameter mutable ?
I have standard libraries that I call from several executables.
In order to set missing / default parameters or override when they have specific
or standard overrides I need to update the parameters from the commandline.
I tried by setting Command::default, but it was not set.
so, if it was possible to change:
impl config::Override for XXXCmd {
fn override_config(
&self,
mut config: XXXConfig,

to
fn override_config(
&mut self,
mut config: XXXConfig,

Or add :
fn override_parameters(&mut self...)

it would solve the problem...

[aawsome]

You could do it vice versa and use the value from the configuration instead of the one given by the commandline in your code.
Then, use override_config to set/override the configuration value depending on the commandline args.