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/image/cubehelix.m	Mon Feb 23 16:42:25 2015 +0000
+++ b/scripts/image/cubehelix.m	Mon Feb 23 14:54:39 2015 -0800
@@ -79,6 +79,7 @@
 
 endfunction
 
+
 %!demo
 %! subplot (1, 2, 1)
 %! rgbplot (cubehelix (256), "composite")