Update todo

TODO.md

@@ -1,10 +1,18 @@
 To-Do List
 ==========
 
-- Binary data/strings: needed for certain values, particular for the File ID
-  and user/owner passwords
-- Copy methods for array, dict, object, page
+- Reference streams
+- Read trailer dict
+- All of the object read/write code
+- All of the stream read/write code
+- Page create method
+- Write out trailer
 - How to handle object references between documents, i.e., if I copy a page from
   one PDF to another, there are a bunch of resources that also need to be
   copied. A dictionary with an object reference can't be copied directly as the
   object number in the new PDF will likely be different than the old one.
+- Security handlers (RC4 + AES, MD5 + SHA-256) for reading encrypted documents.
+- Signature generation/validation code
+- Documentation
+- VS project
+- Run through code analysis tools