do not create or replace 'key_config.ron'

[merikan]

Is your feature request related to a problem? Please describe.
gitui creates the configuration file (~/.config/gitui/key_config.ron) when executed the first time.
If you decide to do some changes to this file to hold your own key-mappings then if an error is found or a key is missing this file is overwritten with new information. Since I have all my config files in git (dotfiles) and the file is just a symlink it will break.

Describe the solution you'd like

1. don't create a file.
2. if a file is found, the file contains only the remaps that the user wants, everything else should be as default
3. If an error is found, ignore the error and show a small error footer in the ui.

Describe alternatives you've considered
If, for some reason, gitui still wants to create the configuration file when executed for the first time. Then a user-created file with the name key_config_user.ron could be used to override some or all settings.

Additional context

thanks for a great project 👍

[extrawurst]

so I used this approach now as a POC for the new feature of allowing the user to customise the key symbol strings: #465

we can use the same approach for this here

[extrawurst]

note https://github.com/extrawurst/gitui/blob/master/KEY_CONFIG.md#key-config