libtmux::unquote

tmux picks one of four forms, and a reader that knows only one corrupts the rest: '' for an empty value; double quotes when the value contains any of / #';${}; single quotes when it contains a double quote; and otherwise no / quotes at all. Inside any of them the body is escaped the way vis does it / — \t, \n, \\, \ooo for a byte with no printable form — and a / leading tilde is escaped whether or not anything else is. / / This is the inverse of tmux's own args_escape, so a value read here and written back is the value that was there.