Release 0.999999

Update hotdoc_lumen_theme

To use the theme, pass to hotdoc:

--html-theme=https://github.com/hotdoc/hotdoc_lumen_theme/releases/download/0.999999/hotdoc_lumen_theme-0.999999.tar.xz?sha256=82f42820a81081a83232c491d72bdcb6ac0eb5b6ba8aa72b4b09f34983bbd5fb

Hotdoc bootstrap theme commit:

commit 6cf1c1305a17688c0bb2a3228ad9d0f3929a43ae
Make enable_search.css a dependency of the main target