Feature proposal: have local config to avoid loosing it on update

[Jeremie-Kiwik]

Here is a feature proposal to address a common problem: when we extract a ZIP file of a newer version of the project onto our current source files, any locally defined configurations are lost because config.php is overwritten.

I propose addressing this issue by introducing the option to have a local configuration file, which would be read if present, instead of the standard file. This approach is similar to the way configuration files are handled in /etc/xx/conf.d on Linux systems.