New BorderShape that embeds the section inside the --list-border
frame, joined to the list content by a horizontal separator with
T-junctions where the list shape has side borders. Requires a list
border with both top and bottom segments; falls back to 'line'
otherwise. Stacks when multiple sections are inline.
Sections inherit --color list-border by default and are colored as a
uniform block via their own --color *-border and *-bg.
Incompatible with --header-first. --header-border=inline requires
--header-lines-border to be inline or unset.
Junegunn Choi
d754cfab87