add ann sent -> sent pointer cast to swig, useful in python

CMakeLists.txt

 PROJECT(Corpus2Library)
 
 set(corpus2_ver_major "1")
-set(corpus2_ver_minor "1")
-set(corpus2_ver_patch "1")
+set(corpus2_ver_minor "2")
+set(corpus2_ver_patch "0")
 
 cmake_minimum_required(VERSION 2.8.0)
 

swig/annotatedsentence.i

@@ -59,6 +59,14 @@ namespace Corpus2 {
     std::string annotation_info() const;
   };
 
+  %extend AnnotatedSentence {
+    static boost::shared_ptr<Sentence> cast_as_sentence(
+      const boost::shared_ptr<AnnotatedSentence>& a)
+    {
+      return a;
+    }
+  }
+
 boost::shared_ptr<Corpus2::AnnotationView> create_view(
         const boost::shared_ptr<AnnotatedSentence>& s,
         const std::string& ann_name);