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/set/union.m
+++ b/scripts/set/union.m
@@ -94,8 +94,7 @@
 %! assert (y, [1, 2, 3, 4, 5]);
 %! assert (y, sort ([a(ia), b(ib)]));
 
-
-%% Test common input validation for set routines contained in validsetargs
+## Test common input validation for set routines contained in validsetargs
 %!error <cell array of strings cannot be combined> union ({"a"}, 1)
 %!error <A and B must be arrays or cell arrays> union (@sin, 1)
 %!error <invalid option: columns> union (1, 2, "columns")