fixing up 'when you really have to loop' activity

Note: I deleted some chunks of text I thought were unnecessary; others might disagree.  (Brian?)

My edits are at http://xtitter.github.io/bjc-r/cur/programming/lists/hof/when-you-really-have-to-loop.html

Text I elided:

(from the first "Try This")
            Technically, <code>for each item</code> isn't a higher order function, 
            because the script in its C-shaped slot isn't a function: It doesn't report a value. 
            (There's a <b><code>report</code></b> block in the script in our example, but 
            that's reporting a value from <code>increasing?</code>, not from the script itself.) 
            But it's a higher-order <i>procedure, </i>because that script in the C-shaped slot 
            is a procedure. All of the C-shaped blocks in the Control palette are higher order 
            procedures, too, although Scratch users don't generally think of them in that way.

Text about "why two ways" with reference to Dan and Brian