Remove line breaks from docblocks

[JDGrimes]

This simply replaces them with spaces.

Should fix #114

[Rarst]

1. Needs cross–platform regex or it will explode into someone's face sooner or later (likely mine). I think we went with replacing [\r\n]+ last time, fixing up issue in wp-cli.
2. Just to be sure, this is after Markdown, so it won't mess with creating paragraphs properly, correct?

[JDGrimes]

1. Forgot about that, I'll add it later today.
2. Yes, the p tags are already present. But there are still line breaks there that get converted to br's on import.

[JDGrimes]

Updated (and with unit tests), although 2639953 should be discarded (I'm not really a git guru :-). Maybe you should just cherry-pick the other 3 commits?

[Rarst]

Maybe you should just cherry-pick the other 3 commits?

Haha, you are so funny... YOLO merge!