Is there an inverse for M-q, some kind of unfill-paragraph-function?
If I have undo data, then it's of course easy. What I am asking for is instead the ability to merge lines in a paragraph into a single long line, right after I have just read the file from disk. This would make it possible to then paste the text into a form (a web form and the like) that is expecting a single linebreak for each paragraph.
In the past I have turned off auto-fill, created a macro to delete an EOL and move to the next line, and applied it repeatedly, but this is getting tiring.