Initial draft support CSS for Markdown Preview

[lkishalmi]

Well, I while ago I've promised to add some CSS config to the Markdown preview, if there is someone who can create a CSS for it.

Well here it is. @Chris2011 I'm pretty un-talented in this CSS, stuff. just registered the viewer.css on most widely used profiles. So this can be tested.

I've needed to use the Editor Settings Storage API in order to get the name of the current profile, so I've opened up that module as friend. However the API is stable enough for years, to be public.

Refinement ideas, are welcome!

Could be a solution for #6652

[lkishalmi]

Well, so far for whatever reason Markdown files used two MIME_TYPE-s text/x-markdown-nb and text/x-markdown probably that was an oversight from the past days.

That made it possible to add the Plain text spellchecking support enabled for these files. it would be good to ignore spell checking in fenced texts, but that obviously needs more work. This addresses #6653

[Chris2011]

Well, so far for whatever reason Markdown files used two MIME_TYPE-s text/x-markdown-nb and text/x-markdown probably that was an oversight from the past days.

That made it possible to add the Plain text spellchecking support enabled for these files. it would be good to ignore spell checking in fenced texts, but that obviously needs more work. This addresses #6653

How is it possible to have 2 different mimetypes for the same file extension?

[lkishalmi]

How is it possible to have 2 different mimetypes for the same file extension?

I think the bug is here: https://github.com/lkishalmi/netbeans/blob/c3dc5eb35cd382ac663db24ea9b79fcc0c725851/ide/markdown/src/org/netbeans/modules/markdown/MarkdownDataObject.java#L112

Where the DataObject which is addigned from the Resolver to the MIME text/x-markdown-nb registers an editor with the MIME text/x-markdown. That's being fixed in this PR.