STYLE: Use default member initialization

Converts a default constructor’s member initializers into the new
default member initializers in C++11. Other member initializers that match the
default member initializer are removed. This can reduce repeated code or allow
use of ‘= default’.

SRCDIR=/Users/johnsonhj/src/jsoncpp/ #My local SRC
BLDDIR=/Users/johnsonhj/src/jsoncpp/cmake-build-debug/ #My local BLD

cd /Users/johnsonhj/src/jsoncpp/cmake-build-debug/
run-clang-tidy.py -extra-arg=-D__clang__ -checks=-*,modernize-use-default-member-init  -header-filter=.* -fix

src/lib_json/json_reader.cpp

@@ -60,8 +60,7 @@ typedef std::auto_ptr<CharReader> CharReaderPtr;
 // ////////////////////////////////
 
 Features::Features()
-    : allowComments_(true), strictRoot_(false),
-      allowDroppedNullPlaceholders_(false), allowNumericKeys_(false) {}
+     {}
 
 Features Features::all() { return {}; }