Markdown code block should have a background

[olivierdalang]

Markdown code highlighting doesn't make code blocks stand out, making it hard to read a markdown document without the preview.

• VSCode Version: 1.19.1
• OS Version: Windosw 10

Steps to Reproduce:

1. Create a markdown file (.md)
2. Create a multiline code block with ```
3. Notice that the block doesn't get any type of rendering, making it hard to follow the document's structure

Here's how it looks like with current VSCode :

Here's an example rendering where code blocks have a different background, much better ! (from sublime with markdown extended package)

[mjbvz]

This would be something a theme could control. Currently blocked by #3429

Closing as duplicate of #3429 + future extension candidate