Split font atlas texture into 1024*1024 size if atlas size > 1024

[sanikoyes]

Resize memory-pool chunk-size in editor/app
Split font atlas texture into 1024*1024 size if atlas size > 1024

[marynate]

Thanks sanikoyes! Multi-page font textures would be very useful for CJK fonts.

One suggestion: you might wanna use "tab" instead of "space" for code indentation. ( Since major Godot existing code indentation are "tab" only )

[akien-mga]

There are merge conflicts in this PR. If the changes are still relevant, could you try to rebase it on top of the current master branch? (and if possible, switch the indentation back to tabs instead of spaces to match the rest of the code)

[akien-mga]

Closing as old.