(set-fill-prefix): start from left-margin.

(set-fill-prefix): start from left-margin.
(fill-region-as-paragraph): don't delete hard newlines.  ignore whitespace
at beginning of region.  Remove justification indentation.
(fill-region): Don't use paragraph-movement commands when use-hard-newlines
is true, just search for hard newlines.
(current-justification): take care at EOB.
(set-justification): new argWHOLE-PAR.  Callers changed.
(justify-current-line): Error if JUSTIFY arg is not reasonable.
Better interaction if there is a fill-prefix.
"Line too long" warning removed.
(unjustify-current-line, unjustify-region): New functions.