Clarify the Output type a little

Author: kojix2

lib/youplot/command.rb

@@ -182,9 +182,9 @@ def output_data(input)
 
     def output_plot(plot)
       case options[:output]
-      when IO
+      when IO, StringIO
         plot.render(options[:output])
-      else
+      when String, Tempfile
         File.open(options[:output], 'w') do |f|
           plot.render(f)
         end
@@ -193,7 +193,7 @@ def output_plot(plot)
 
     def output_plot_progressive(plot)
       case options[:output]
-      when IO
+      when IO, StringIO
         # RefactorMe
         out = StringIO.new(String.new)
         def out.tty?

test/youplot/iris_test.rb

@@ -28,6 +28,7 @@ def setup
 
   def teardown
     @stderr_file.close
+    @stdout_file.close
   end
 
   def fixture(fname)

test/youplot/simple_test.rb

@@ -28,6 +28,7 @@ def setup
 
   def teardown
     @stderr_file.close
+    @stdout_file.close
   end
 
   def fixture(fname)