create output dirs before writing files

bin/rocco

@@ -11,6 +11,7 @@
 #/       --help             Show this help message
 
 require 'optparse'
+require 'fileutils'
 
 # Write usage message to stdout and exit.
 def usage(stream=$stderr, status=1)
@@ -77,13 +78,11 @@ rescue LoadError
   raise
 end
 
-# Create the output directory if it doesn't already exist.
-Dir.mkdir output_dir if !File.directory?(output_dir)
-
 # Run each file through Rocco and write output.
 sources.each do |filename|
   rocco = Rocco.new(filename, sources, options)
   dest = File.join(output_dir, filename.split('.')[0..-2].join('.') + '.html')
   puts "rocco: #{filename} -> #{dest}"
+  FileUtils.mkdir_p File.dirname(dest)
   File.open(dest, 'wb') { |fd| fd.write(rocco.to_html) }
 end