A configuration tool that will auto-generate Marlin binaries
The idea of this tool, is to allow you to declare only the changes to Marlin that matter to you, by using a GUI or a simple JSOn file, rather than cloning and managing your own fork.
Marlin is an awesome project. There is one thing that has bothered me though, which is the need to maintain configuration within the version controlled source, instead of that source being able to ingest external configuration. Let me expand on this a bit.
Over the last few years, I've spent time working with infrastructure automation, and I've also spent time using Funcional Reactive Programming for software I've written. The one thing that has been common among those two things is a declaritive approach to problem solving. Declarative in this case means describing to the computer what you want to achieve, as oppossed to describing to the computer how to achieve something (called an imperative approach).
The typical procedure for building Marlin is to clone Marlin, and then modify header files to achieve the configuration you desire. This seems like a smell to me.
At the moment, configuring Marlin feels very imperative to me. Every new merge request to Marlin requires you to merge or rebase your own configuration, and this makes it very easy to introduce mistakes to your configuration that can damage your hardware.
To me, the right approach would allow me to describe what changes my printer wants, and be able to apply that to any version of Marlin, and achieve the correct binary as a result.