Allow outputting to stdout for consistency with markdown

markdown-pp.py

@@ -7,13 +7,17 @@
 import MarkdownPP
 
 if len(sys.argv) > 2:
-	infile = sys.argv[1]
-	outfile = sys.argv[2]
+	mdpp = open(sys.argv[1], "r")
+	md = open(sys.argv[2], "w")
+
+elif len(sys.argv) > 1:
+	mdpp = open(sys.argv[1], "r")
+	md = sys.stdout
+
 else:
 	sys.exit(1)
-
-mdpp = open(infile, "r")
-md = open(outfile, "w")
 
 MarkdownPP.MarkdownPP(input=mdpp, output=md, modules=MarkdownPP.modules.keys())
 
+mdpp.close()
+md.close()

readme.mdpp

@@ -32,7 +32,7 @@ to the module, `markdown-pp.py`.
 Assuming you have a file named `foo.mdpp`, you can generate the preprocessed
 file `foo.md` by running the following command:
 
-    $ path/to/markdown-pp.py foo.mdpp foo.md
+    $ path/to/markdown-pp.py foo.mdpp > foo.md
 
 Because the current CLI script is very simple, it just automatically selects
 all available modules for the preprocessor to use.  I will eventually get to