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/help/print_usage.m
+++ b/scripts/help/print_usage.m
@@ -113,7 +113,7 @@
     endl_idx = find (help_text == "\n");
     buffer = "";
     for k = 1:length (def_idx)
-      endl = endl_idx (find (endl_idx > def_idx(k), 1));
+      endl = endl_idx(find (endl_idx > def_idx(k), 1));
       if (isempty (endl))
         buffer = strcat (buffer, help_text (def_idx(k):end), "\n");
       else