Markdown Panel Update

[d.healey]

@Christoph-Hart I'm making a tutorial for the markdown panel at the moment. The one thing I can't get it to do is update from a server. I've put my .dat files in a public github repo, inside a subfolder called cache. I set the server update URL for the panel to that repo (with the trailing /) but when I click to update the docs I get a Can't connect to server message. I've also tried uploading them to a public folder on my own server just in case it was a github thing.

I also don't think the update dialog is very end user friendly. And I didn't see a method to remove the documentation edit/lock button from the toolbar which is quite important.