[markdown mode] Fix inappropiate behavior of continuelist addon

[marcelgerber]

Steps to reproduce the issue:

1. Go to http://codemirror.net/mode/markdown/index.html
2. Replace all the text with - -- (which is a horizontal ruler)
3. Press Enter

Result:

- --
- 

Expected:

- --

The issue was that state.quote, a numeric value, was compared to false.

I also improved the markdown mode a tiny bit.

[marijnh]

I think my patch is less invasive, but if it misses something your patch solves, let me know.

[marcelgerber]

I just noticed inQuote won't ever be false, for the reasons I wrote above.

[marijnh]

Ah, you are entirely right. I didn't expect an unrelated patch in the pull request, and completely misinterpreted the code. I've merged your solution instead, as well as your cleanup patch.

[marcelgerber]

Well, I don't exactly know why, but this fix (and yeah, to be honest, it looks pretty unrelated) fixed the issue for me!

[marcelgerber]

For little more background:
As inQuote was always true, !inList && !inQuote in the if condition was always false, even though inList was correctly set to false.

Thus, it should still work after you revert your unneeded commit.