LaTeX reformat

[David Rasmussen]

In plain emacs (I am not using AucTeX as I have not been able to find it 
anywhere), I use "Auto Fill", to make it wrap lines automatically. When 
I have fiddled around with the text a bit, the automatically inserted 
newlines are at random places so the text looks broken up (in emacs).

A way to solve this, is to delete the now extraneous newline, and then 
go to the end of the line, and press space. This causes the whole line 
to get reformatted.

But it would be nice if I could just mark an entire region and reformat 
it, so that newlines were at the right places, and lines wrapped 
naturally. What is the command for this?

/David