Rework a part of the codebase to accomodate with Quadrum changes and make it a mod instead of an expansion

[Guerro323]

Since PataNext was already based on Quadrum, there needs to be some changes made to accommodate with the newest Quadrum changes (such as move to flecs for the ECS and revghost.v2).

The codebase needs to be structured more as a mod rather than an expansion of Quadrum (since PataNext isn't a 'game' anymore)

[Guerro323]

Quadrum vision has diverged too much from the original goal.
As such it's not possible for PataNext to be a mod as it would require too much code to support the old gameplay, and would get cumbersome for the future of both projects, limiting both the vision of Quadrum and features/possibilities of PataNext.

PataNext will have its own codebase again, some parts of the code will still be shared (base of rhythm & abilities, networking, proxies, etc...)

Note

While it's an happy news for PataNext players, I still consider it as a non primary focus of development.

I've already started some weeks ago on splitting the codebase, there is only the networking left to implement; there will be more details in the incoming devlog.