Updated with architectural notes.

TODO

@@ -9,3 +9,17 @@
 * Improve documentation, both of the code and Textile syntax.
   The previous version of pytextile had excellent inline documentation;
   similarly, docstrings such as "What does this do?" should be improved.
+
+* Address outstanding architectural issues:
+  The Textile class has a large number of public methods which are, in fact,
+  not intended to be called by the public.
+  Also, some parameters are set in __init__(), while others are set in
+  textile().
+  Because various instance variables get set while text is being processed,
+  a Textile object cannot be reused--that is, it is not possible to set up
+  a Textile object with the desired parameters, and then use it repeatedly
+  to process multiple strings, because parameters such as the shelf do not
+  get reset between calls to textile().
+
+* If we want to re-implement sanitization or validation, it should probably be
+  done with html5lib.