CodeMirror CSS should be scoped to EasyMDE

[infime]

Describe the bug

Some CSS selectors (specifically .CodeMirror) are too broad and affect other instances of CodeMirror in an application.

To Reproduce

Import EasyMDE CSS into an app that is already using CodeMirror. Other instances of CodeMirror will have styles intended specifically for EasyMDE applied.

Expected behavior

EasyMDE CSS to only affect it's instance(s) of CodeMirror.

I'd be happy to get this going in a PR.

[Ionaru]

I've added extra scoping to the CSS, please try the @next version to see if that solves your issues.

[infime]

@Ionaru works great, thanks!