v1.3.1

A small but important release with a bug fix for those using usagi.conf. It
wasn't included in the exported game binary bundle, meaning the settings
wouldn't apply. That's fixed now, as well as some other bugs and additions
below.

Download the executable below, run usagi update, or update via Homebrew
if you install it that way.

Features:

• New util.ease.* functions by curbs; see
  PR #104;
  view the docs
• Setting gif_length config value to 0 disables the GIF recorder, removing
  the small bit overhead associated; useful if you are developing or testing on
  older hardware; see #69
• GIF recorder only runs in dev mode with usagi dev; exported games and
  usagi run do not not run the recorder so that the overhead of running it is
  not passed onto players, especially those on less powerful hardware; players
  who want to record their gameplay have their own means and the GIF recorder in
  Usagi is meant as an easy way for devs to share their game progress. It's also
  imperfect since effects like screenshake don't come through. So it's now dev
  mode-only. See #69

Fixes:

• Exported games properly include usagi.conf, applying configuration values as
  expected; thanks to curbs for the fix; see
  #115
• Save Inspector tool properly reads game_id from usagi.conf; see
  #108