Output a conditional newline to STREAM (which defaults to
STANDARD-OUTPUT) if it is a pretty-printing stream, and do
nothing if not. KIND can be one of:
:LINEAR - A line break is inserted if and only if the immediately
containing section cannot be printed on one line.
:MISER - Same as LINEAR, but only if ``miser-style’’ is in effect.
(See PRINT-MISER-WIDTH.)
:FILL - A line break is inserted if and only if either:
(a) the following section cannot be printed on the end of the
current line,
(b) the preceding section was not printed on a single line, or
(c) the immediately containing section cannot be printed on one
line and miser-style is in effect.
:MANDATORY - A line break is always inserted.
When a line break is inserted by any type of conditional newline, any
blanks that immediately precede the conditional newline are omitted
from the output and indentation is introduced at the beginning of the
next line. (See PPRINT-INDENT.)