Release 0.16

Update hotdoc_lumen_theme

To use the theme, pass to hotdoc:

--html-theme=https://github.com/hotdoc/hotdoc_lumen_theme/releases/download/0.16/hotdoc_lumen_theme-0.16.tar.xz?sha256=b7d7dde51285d1c90836c44ae298754e4cfa957e9a6d14ee5844b8a2cac04b5a

Hotdoc bootstrap theme commit:

commit ba24bed2fe0bda41f1ac61d90ec8f5a322a0e5a8
Remove cookie access from style-switcher

- Remove setCookie() and readCookie() functions
- Convert, but comment out, window.onunload handler. The style is
  stored at the start of the setActiveStyleSheet() call (since the
  localStorage API is quicker & less intensive than using cookies),
  which makes onunload-driven updating unnecessary/redundant.