Log Message:
Update to 1.78. From the changelog:

* Correct an optimization bug introduced in 1.76. Reported by Tom
  Roostan.
* Major improvements to color selection (important when reducing
  colormap size). Use gamma-corrected colors in selection and
  dithering; this makes image quality much better. Also, when reducing
  colors with dithering, prefer to select colors that dithering can't
  approximate.
* Add ordered dithering modes, which avoid animation artifacts. The
  default ordered dithering mode (`--dither=ordered`) is a novel mode
  that combines some of the visual advantages of error diffusion with
  the artifact avoidance of ordered dithering.
* Add halftone dithering (`--dither=halftone`).
* gifview: Improved cache memory management for better animations.
  Collect memory for old frames based on an explicit --memory-limit
  (default 40MB).
* gifview: Add `--fallback-delay` option, to specify a fallback delay
  for frames with delay 0. Thanks to Sung Pae.
* Fix `-O2` crashes introduced with `--resize` improvements. Reported
  by Bryan Stillwell.
* Improve `--careful` (fewer crashes). Reported by Bryan Stillwell.
* Improve `-O2`: again, don't refuse to optimize images with local
  color tables. Reported by Bryan Stillwell.
* Greatly improve `--dither` speed.
* Improve `--resize` behavior: avoid animation artifacts due to
  different rounding decisions. Also speed it up. Reported by Bryan
  Stillwell.
* Fix bug where `-O2` would refuse to optimize some images with local
  color tables, claiming that "more than 256 colors were required".
  What was really required is previous disposal. Reported by Bryan
  Stillwell.
* Fix crash bugs on some combinations of `--crop` and `--resize`
  (prevalent on images whose first frame didn't cover the whole
  logical screen). Reported by Bryan Stillwell.