rm tempfile workaround; clone dw-free to $LJHOME

From the discussion here:
https://github.com/dreamwidth/dw-free/pull/355#discussion_r3920545
it's not common or encouraged for people to put dw-free directly
into $HOME.  Thus, we can remove the tempfile dance and simplify
the code a bit.
+messaging re use of dw-nonfree.

Also, clean up a few messages to bring lines under 72 chars.