Details:
- Renamed test/3/matlab to test/3/octave.
- Within test/3, updated and tuned plot_l3_perf.m and plot_panel_4x5.m
files for use with octave (which is free and doesn't crash on me
mid-way through my use of subplot).
- Updated runthese.m scratchpad for zen2 invocations.
- Added Nikolay S.'s subplot_tight() function, along with its license.