The overloading of IR emits magic \X'...' sequences that turn into HTML manual links.
But not all such IR invocations should be manual links;
those had to be written to avoid the IR macro before.
Worse, the \X'...' ending the IR causes troff to emit only a single space after a period.
Defining a new IM macro for manual references fixes both problems.
Fixes#441.
This fixes at least one shell script (printfont) that expected
'x'`{y}'z'
to mean
'x'^`{y}^'z'
as it now does. Before it meant:
'x'^`{y} 'z'
One surprise is that adjacent lists get a free carat:
(x y z)(1 2 3)
is
(x1 y2 z3)
This doesn't affect any rc script in Plan 9 or plan9port.
