add option to use soft breaks for markdown rendering

[tessus]

This PR adds an option to settings to use the traditional line-break behavior.

It is marked as Work In Progress because of the following 2 items:

• I added the option under General because it's a general markdown setting. We can always move it to a different section.
• I used a separate variable breaks_, because I thought it made the code more readable. I can remove it and use the ternary operation directly. Please advise.

[tessus]

fixes #1406

[laurent22]

I'd prefer all the Markdown rendering options to be under the same section - I think for users it will be easier to find. For now, to keep it simple, let's put it under the "plugins" section (it's not really a plugin but maybe later we can rename the section or arrange things differently).

Also it means we can remove the description from the setting because from the section it will be implied it's about Markdown (as much as possible, it's better to reduce the localisable text we add to the app).

[tessus]

I will put it under the plugins sections. I am on my way out, so I will look into it tomorrow.

[tessus]

@laurent22 I've put it under the section "plugins". While I do understand that you want to minimize localizable text (which makes sense btw), I am afraid that the term "soft breaks" might not be understood easily, therefore I changed the text to Enable traditional markdown line-break behaviour. This makes it definitely clearer. But if you really want it to just read Enable soft breaks, please let me know. (In that case we should add the explanation for the different plugins to the documentation.)

[laurent22]

I see what you mean but no matter what text we choose, it's an advanced setting that most users won't need (I only remember one person who ever asked about it), and Enable traditional markdown line-break behaviour won't mean much as most people aren't expert in Markdown and don't know what's a traditional line-break.

So I'd prefer to keep it short and use Enable soft breaks - the one user who cares about it will know what it means :-) and the rest can ignore it. Adding more info to the Readme of course is fine.

[tessus]

Ok, here you go...

[laurent22]

Perfect, thanks @tessus!

[tessus]

You are welcome!

[taw00]

Woot. The one user that cares about it... really cares about it :)
Seriously though. Anyone that uses a markdown editor for more than short notes, starts to care about this. :) Regardless, thank you for implementing.

[tessus]

@taw00 it also came up on github and I also know people who use the traditional format. So you might not be the only one, but you were the one who was the most vocal about it. ;-)

[Nebucatnetzer]

And I lived with the illusion that my fantastic issue sparked the development :D