maint: Clean up m-files to follow Octave coding conventions. Try to trim long lines to < 80 chars. Use '##' for single line comments. Use '(...)' around tests for if/elseif/switch/while. Abut cell indexing operator '{' next to variable. Abut array indexing operator '(' next to variable. Use space between negation operator '!' and following expression. Use two newlines between endfunction and start of %!test or %!demo code. Remove unnecessary parens grouping between short-circuit operators. Remove stray extra spaces (typos) between variables and assignment operators. Remove stray extra spaces from ends of lines.

--- a/scripts/plot/util/private/__gnuplot_ginput__.m
+++ b/scripts/plot/util/private/__gnuplot_ginput__.m
@@ -117,7 +117,8 @@
           endif
           fclear (istream);
         endwhile
-        [x(k), y(k), button(k), count] = sscanf (str{end}(8:end), "%f %f %d", "C");
+        [x(k), y(k), button(k), count] = ...
+          sscanf (str{end}(8:end), "%f %f %d", "C");
       endif
 
       if ([x(k), y(k), button(k)] == [0, 0, -1])