linear time proof of size is easy

... if you put the ++1 in the right place!

Move it down past the two recursive calls and the goals
generated by program aren't true.
attempt to sort out the running time of size
In playing around I needed this, so I added it for now
move the files around to have more sensible names

also, move the stuff that's not expected to be in the
future into the old/ directory

(and add some parens to insert to fix indentation)
add a little visualizer to see what the trees look like at different sizes

run 'slideshow size-scratch.rkt' to see it, or run drracket and

  (require (submod "." slideshow))

at the prompt
show diff's path too
show a few more trees.
figured out a non-closed-form version of the running time of size

... have to wonder if there is another way to compute this
that doesn't involve a loop, tho!
indentation
added cl_log