Removed a static variable used to contain the current recursion depth of Reader::readValue(). The number of elements in an internal container Reader::nodes_ is used instead. It is correct because any recursive call of Reader::readValue() is executed with adjacent nodes_.push() and nodes_.pop() calls.
Added the option to change the allowed recursion depth at compile time by defining a macro JSONCPP_STACK_LIMIT as the required integer value.
Rename variable empty to emptyString in Value constructor to avoid shadowing of Value::empty().
GCC 4.8 produces the warning about this:
lib_json/json_value.cpp: In constructor ‘Json::Value::Value(Json::ValueType)’:
lib_json/json_value.cpp:346:27: warning: declaration of ‘empty’ shadows a member of 'this' [-Wshadow]
As per discussion in - https://github.com/open-source-parsers/jsoncpp/issues/404
Null should not be pass to memcmp, it may show undesired behaviour, so avoid doing that using assertion.
Also, changed one direct "assert" to JSON_ASSERT - it will be decided if exceptions are used or not.
See https://github.com/open-source-parsers/jsoncpp/issues/411#issuecomment-180974558
I was unable to produce a warning in Clang, so I am not certain. But based on a [SO answer](http://stackoverflow.com/questions/25480059/gcc-conversion-warning-when-assigning-to-a-bitfield), I think I've fixed the following:
```
/tmp/jsoncpp/src/lib_json/json_value.cpp: In copy constructor 'Json::Value::CZString::CZString(const Json::Value::CZString&)':
/tmp/jsoncpp/src/lib_json/json_value.cpp:235:18: error: conversion to 'unsigned char:2' from 'unsigned int' may alter its value [-Werror=conversion]
storage_.policy_ = (other.cstr_
~~~~~~~~~~~~
? (static_cast<DuplicationPolicy>(other.storage_.policy_) == noDuplication
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
? noDuplication : duplicate)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
: static_cast<DuplicationPolicy>(other.storage_.policy_));
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```
