Fully implement string interning.

Also, more const.

Change-Id: I09cae88d677e8e6e42d0fa9b5d1093c79d225e66
diff --git a/src/image.h b/src/image.h
index c567880..94824d7 100644
--- a/src/image.h
+++ b/src/image.h
@@ -49,7 +49,7 @@
   // required base address for mapping the image.
   uint32_t base_addr_;
 
-  // absolute address of an Object[] of Strings to InternTable::Register
+  // absolute address of an Object[] of Strings to InternTable::RegisterStrong.
   uint32_t intern_addr_;
 };