Growable Buffer: baseline performance tests

[ianna]

[ianna]

@jpivarski - as discussed, here are the plots.

[jpivarski]

The PDFs will be useful for talks, but for looking up this page, it will help to have large PNGs.

Words to include here so that we can find them later: GrowableBuffer panel panels std::vector like exponential memory growth versus linear speed time seconds performance allocation memcpy malloc calloc