[Feature Request] Add settings to change undo history interval

[Andr3wD]

Maybe add a setting to change the undo history interval so smaller undo-s can be done? Might be too out of scope for this plugin.

[Andr3wD]

I believe this can be done with historyEventDelay at https://codemirror.net/doc/manual.html#config and setOption part of CodeMirror.Vim. I'm offering to implement this, but I'm not sure if it's too out of scope for this plugin or not.

[esm7]

IMHO any option that's available in CodeMirror and interests some users is worth exposing through a Vimrc setting. If you want to control this for yourself then I guess it's interesting. I'd define it as an option (CodeMirror.Vim.defineOption), and since there doesn't seem to be a Vim equivalent of it, use the name as it is in CodeMirror (historyEventDelay).