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/doc.m
+++ b/scripts/help/doc.m
@@ -54,7 +54,7 @@
     endif
 
     ## if GUI is running, let it display the function
-    if isguirunning ()
+    if (isguirunning ())
       __octave_link_show_doc__ (fname);
     else