Feature request: Allow more config options than just for the toolbar

[passchn]

I could extend the Config class to have my own toolbar config, or to disable the toolbar, however, other options such as for the status bar or the spell checker are one level above the toolbar in the simpleMDE configuration in javascript.

In the file vendor/silverstripers/markdown/client/src/components/MarkdownEditorField/MarkdownEditorField.js on line 157 every other option such as spellChecker: false won't reach the simpleMDE options.

It would be nice to be able to pass higher level configuration options as defined here:
https://github.com/sparksuite/simplemde-markdown-editor#configuration