Refactoring core.ts

Hi,

While working on another PR I noticed that `core.ts` was extremely long and it was a little hard to figure out how to implement some changes so I am planning on refactoring that code into multiple modules to make it more maintainable.
For example, `core.ts` has 98 functions
```bash
$ grep -c "= () =>" src/livecodes/core.ts
98
```

So I am thinking we could extract some modules from `core.ts` like a ConfigManager, EditorManager, StorageManger, etc. without changing the functions and then later we can refactor the long functions.

This might be too much for a single PR so maybe break the PRs into something like extracting ConfigManger from core.ts, extracting x etc.

What do you think?