This patch adds support for DECRQSS (request Selection or Setting),
for the following sub-queries:
* DECSTBM Set Top and Bottom Margins
* SGR Set Graphic Rendition
* DECSCUSR Set Cursor Style
Closes#798
Using underlining for parameters allows the angle brackets to be
removed while still keeping a visual separation between literals
and parameters. The removes any uncertainty about whether the
angle brackets are part of the sequence or not. It also mirrors
the formatting used further down in the document.
There's no mention of SS0 or SS1 functions in ECMA-48 or ECMA-35.
0x0E/0x0F are SO/SI (Shift In/Out) in "7-bit environments" or LS0/LS1
(Locking Shift 0/1) in "8-bit environments". The former is the one
that applies to foot, since it generally follows "7-bit" conventions
due to its use of UTF-8.
See also: ECMA-35 §7.2 and §9.2.
In a recent Debian build from master, Lintian complained about a bad
whatis entry for this manual page. The tag description [1] says a NAME
section is required. It is added here.
[1] https://lintian.debian.org/tags/bad-whatis-entry.html
