Offer choice between between markdown and html editing for new content

[CrispinF]

Original issue title: "Toggle between markdown and html editing (when configured for markdown)"

This page https://www.cloudscribe.com/using-markdown explains configuration options for markdown. It seems it should be possible to implement a toggle between editing as markdown and html in the editor once opened, if markdown has been enabled through configuration.
A complication might be if a user tried to toggle with unsaved edits... perhaps this should force a "save as draft".

[joeaudette]

my recollection is that content instances cannot be changed from one to another format once created. Certainly can't reverse html to markdown. You can make any new content use either one no matter which is the default.

[CrispinF]

@joeaudette ah that explains why I couldn't switch using querystring parameters either. I was led astray by this in the docs "When you go the the edit page for a new item just append "?type=markdown" or, if there is already a query string, append "&type=markdown" (without the quotes of course)" I somehow interpreted that as meaning we could switch for existing content as well. doh!
I cannot really see anyone ever manipulating the querystring in that way - a bit obscure. Would another option be to provide two options when creating content (when markdown is configured) e.g. a second button here for "... (markdown)":

[joeaudette]

markdown is always enabled, the setting just makes it the default.

I would not add more buttons and more choices. The only ones who are ever going to use markdown are developers and they know how to use a query string if they want to make some content in the non default format.

I actually doubt there is anyone out there using the markdown feature at all and not sure it should ever have been included, just was trying to appeal to developers. No-one has asked for any new features or improvements to it or given any feedback at all. Seems like developers who like markdown like to generate their sites with static site generators and keep their markdown in github files.

I think there is a config setting to hide the markdown option in settings and probably should hide it by default if it isn't already since the vast majority will never need to know about it.

[CrispinF]

OK - noted about enabling.

I find that most of my non-developer colleagues are now familiar with markdown, through use of things like GitHub Wikis, and some prefer this to html editors. That's why I think nowadays this is a legitimate alternative for many users not just developers.

The option to make markdown the default (in site settings) only appears if config contains "ShowDefaultContentType": true and that's not the default.

So I'm thinking it would be reasonable to show two Create options, but only if we added a another config option to enable this. Not a high priority though.