Assume C++11

We already assume C++11 elsewhere, so all pre-11 `#ifdef` branches are
dead code at this point. Fixes issue #1591 because we can just use
`std::isfinite` etc.

assume C++11 in json_reader.cpp as well

apply clang-format

AUTHORS

diff --git a/AUTHORS b/AUTHORS
index e1fa0fc..7a3def2 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -16,7 +16,7 @@
 Ben Boeckel <mathstuf@gmail.com>
 Benjamin Knecht <bknecht@logitech.com>
 Bernd Kuhls <bernd.kuhls@t-online.de>
-Billy Donahue <billydonahue@google.com>
+Billy Donahue <billy.donahue@gmail.com>
 Braden McDorman <bmcdorman@gmail.com>
 Brandon Myers <bmyers1788@gmail.com>
 Brendan Drew <brendan.drew@daqri.com>

src/lib_json/json_reader.cpp

diff --git a/src/lib_json/json_reader.cpp b/src/lib_json/json_reader.cpp
index 10c97ae..5b62999 100644
--- a/src/lib_json/json_reader.cpp
+++ b/src/lib_json/json_reader.cpp
@@ -23,13 +23,6 @@
 #include <utility>
 
 #include <cstdio>
-#if __cplusplus >= 201103L
-
-#if !defined(sscanf)
-#define sscanf std::sscanf
-#endif
-
-#endif //__cplusplus
 
 #if defined(_MSC_VER)
 #if !defined(_CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES)
@@ -53,11 +46,7 @@
 
 namespace Json {
 
-#if __cplusplus >= 201103L || (defined(_CPPLIB_VER) && _CPPLIB_VER >= 520)
 using CharReaderPtr = std::unique_ptr<CharReader>;
-#else
-using CharReaderPtr = std::auto_ptr<CharReader>;
-#endif
 
 // Implementation of class Features
 // ////////////////////////////////

src/lib_json/json_writer.cpp

diff --git a/src/lib_json/json_writer.cpp b/src/lib_json/json_writer.cpp
index ee45c43..e5b5dd8 100644
--- a/src/lib_json/json_writer.cpp
+++ b/src/lib_json/json_writer.cpp
@@ -10,6 +10,8 @@
 #include <algorithm>
 #include <cassert>
 #include <cctype>
+#include <cmath>
+#include <cstdio>
 #include <cstring>
 #include <iomanip>
 #include <memory>
@@ -17,67 +19,6 @@
 #include <sstream>
 #include <utility>
 
-#if __cplusplus >= 201103L
-#include <cmath>
-#include <cstdio>
-
-#if !defined(isnan)
-#define isnan std::isnan
-#endif
-
-#if !defined(isfinite)
-#define isfinite std::isfinite
-#endif
-
-#else
-#include <cmath>
-#include <cstdio>
-
-#if defined(_MSC_VER)
-#if !defined(isnan)
-#include <float.h>
-#define isnan _isnan
-#endif
-
-#if !defined(isfinite)
-#include <float.h>
-#define isfinite _finite
-#endif
-
-#if !defined(_CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES)
-#define _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES 1
-#endif //_CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES
-
-#endif //_MSC_VER
-
-#if defined(__sun) && defined(__SVR4) // Solaris
-#if !defined(isfinite)
-#include <ieeefp.h>
-#define isfinite finite
-#endif
-#endif
-
-#if defined(__hpux)
-#if !defined(isfinite)
-#if defined(__ia64) && !defined(finite)
-#define isfinite(x)                                                            \
-  ((sizeof(x) == sizeof(float) ? _Isfinitef(x) : _IsFinite(x)))
-#endif
-#endif
-#endif
-
-#if !defined(isnan)
-// IEEE standard states that NaN values will not compare to themselves
-#define isnan(x) ((x) != (x))
-#endif
-
-#if !defined(__APPLE__)
-#if !defined(isfinite)
-#define isfinite finite
-#endif
-#endif
-#endif
-
 #if defined(_MSC_VER)
 // Disable warning about strdup being deprecated.
 #pragma warning(disable : 4996)
@@ -85,11 +26,7 @@
 
 namespace Json {
 
-#if __cplusplus >= 201103L || (defined(_CPPLIB_VER) && _CPPLIB_VER >= 520)
 using StreamWriterPtr = std::unique_ptr<StreamWriter>;
-#else
-using StreamWriterPtr = std::auto_ptr<StreamWriter>;
-#endif
 
 String valueToString(LargestInt value) {
   UIntToStringBuffer buffer;
@@ -129,12 +66,12 @@
   // Print into the buffer. We need not request the alternative representation
   // that always has a decimal point because JSON doesn't distinguish the
   // concepts of reals and integers.
-  if (!isfinite(value)) {
+  if (!std::isfinite(value)) {
     static const char* const reps[2][3] = {{"NaN", "-Infinity", "Infinity"},
                                            {"null", "-1e+9999", "1e+9999"}};
-    return reps[useSpecialFloats ? 0 : 1][isnan(value)  ? 0
-                                          : (value < 0) ? 1
-                                                        : 2];
+    return reps[useSpecialFloats ? 0 : 1][std::isnan(value) ? 0
+                                          : (value < 0)     ? 1
+                                                            : 2];
   }
 
   String buffer(size_t(36), '\0');