Use emplace() instead of insert() in some places.

Leads to (possibly faster) and shorter code.

src/Context.cpp

@@ -337,7 +337,7 @@ Context::Context() {
     std::unordered_map<std::string, Extension> futureExtensions;
     for(std::size_t i = future; i != versions.size(); ++i)
         for(const Extension& extension: Extension::extensions(versions[i]))
-            futureExtensions.insert(std::make_pair(extension._string, extension));
+            futureExtensions.emplace(extension._string, extension);
 
     /* Check for presence of extensions in future versions */
     #ifndef MAGNUM_TARGET_GLES2

src/MeshTools/RemoveDuplicates.h

@@ -127,7 +127,7 @@ template<class Vertex, std::size_t vertexSize> void RemoveDuplicates<Vertex, ver
                exists, change vertex pointer of the face to already
                existing vertex */
             HashedVertex v(*it, table.size());
-            auto result = table.insert(std::pair<Math::Vector<vertexSize, std::size_t>, HashedVertex>(Math::Vector<vertexSize, std::size_t>::from(index), v));
+            auto result = table.emplace(Math::Vector<vertexSize, std::size_t>::from(index), v);
             *it = result.first->second.newIndex;
         }
 

src/ResourceManager.h

@@ -469,7 +469,7 @@ template<class T> void ResourceManagerData<T>::set(const ResourceKey key, T* con
 
     /* Insert it, if not already here */
     } else if(it == _data.end())
-        it = _data.insert(std::make_pair(key, Data())).first;
+        it = _data.emplace(key, Data()).first;
 
     /* Replace previous data */
     delete it->second.data;