fixed #135: operator[] now only works on nonconst JSON objects

README.md

@@ -42,11 +42,9 @@ to the files you want to use JSON objects. That's it. Do not forget to set the n
 
 Though it's 2015 already, the support for C++11 is still a bit sparse. Currently, the following compilers are known to work:
 
-- GCC 4.9 - 5.2
-- Clang 3.4 - 3.7
-- Microsoft Visual C++ 14.0 RC
-
-Note using GCC 4.8, the unit tests cannot be compiled due to a [bug in the preprocessor](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55971).
+- GCC 4.9 - 5.2 (and possible later)
+- Clang 3.4 - 3.7 (and possible later)
+- Microsoft Visual C++ 14.0 RC (and possible later)
 
 I would be happy to learn about other compilers/versions.