Added managed AST conversion code for statements and expressions.

Author: tritao

src/AST/Function.cs

@@ -250,6 +250,7 @@ public QualifiedType OriginalReturnType
         public string Mangled { get; set; }
         public string Signature { get; set; }
         public string Body { get; set; }
+        public Stmt BodyStmt { get; set; }
 
         public override T Visit<T>(IDeclVisitor<T> visitor)
         {

src/AST/SourceLocation.cs

@@ -87,4 +87,8 @@ public override string ToString()
             return IsMacroID ? "Macro ID: " + ID : "File ID: " + Offset;
         }
     }
+
+    public struct SourceRange
+    {
+    }
 }