use more emplace_back

Signed-off-by: Rosen Penev <rosenp@gmail.com>

samples/Jzon.cpp

@@ -448,11 +448,11 @@ namespace Jzon
 
     void Object::Add(const std::string &name, Node &node)
     {
-        children.push_back(NamedNodePtr(name, node.GetCopy()));
+        children.emplace_back(name, node.GetCopy());
     }
     void Object::Add(const std::string &name, const Value &node)
     {
-        children.push_back(NamedNodePtr(name, new Value(node)));
+        children.emplace_back(name, new Value(node));
     }
     void Object::Remove(const std::string &name)
     {

src/exif.cpp

@@ -585,7 +585,7 @@ namespace Exiv2 {
         ExifKey exifKey(key);
         auto pos = findKey(exifKey);
         if (pos == end()) {
-            exifMetadata_.push_back(Exifdatum(exifKey));
+            exifMetadata_.emplace_back(exifKey);
             return exifMetadata_.back();
         }
         return *pos;

src/iptc.cpp

@@ -265,7 +265,7 @@ namespace Exiv2 {
         IptcKey iptcKey(key);
         auto pos = findKey(iptcKey);
         if (pos == end()) {
-            iptcMetadata_.push_back(Iptcdatum(iptcKey));
+            iptcMetadata_.emplace_back(iptcKey);
             return iptcMetadata_.back();
         }
         return *pos;