"make doc" from best examples METHOD available

Previously "make doc" was breaking for me on a build that didn't
include opt in METHODS

It looks like we had the .php file depending on (and running??) all of opt, dbg, and devel?

Now we look for the fastest method available and run the examples for that method alone when doing "make doc".

There's still work to be done here (out-of-source build docs currently have to be stitched together from build dir and source dir outputs by hand?) but this ought to be a step forward.