Support Raw Mode Edit

[clsource]

For speedy thinkering
maybe a "Raw" mode to directly edit the markdown code behind the livemd file.

This mode would not be able to execute the code. Only to edit the source file
for quicker fixes and raw markdown.

When saved, livebook will reload the livemd file and you can continue to use as normal.

Possible buttons:

• Save and Reload
• Save and Continue Editing

Maybe some UI similar to the Export

Currently for quicker fixes to the markdown I have to:

1. Close the livebook session
2. Open the livemd in an external editor
3. Reopen the livemd file with Livebook

[josevalim]

This has been proposed a couple times, so I recommend checking past discussions, but there are limitations going this route, especially because we sign notebooks for authenticity, and smart cells and more. :)

[clsource]

Thanks 👍 I understand.