Fixed compilation issue.

"insert_or_assign" was not defined in the Visual Studio 2013 toolset.

code/MDL/HalfLife/HL1MDLLoader.cpp

@@ -665,7 +665,7 @@ void HL1MDLLoader::read_meshes() {
      */
     auto AddTrivertToBone = [&](int bone, short trivert_index) {
         if (bone_triverts.count(bone) == 0)
-            bone_triverts.insert_or_assign(bone, std::set<short>{ trivert_index });
+            bone_triverts.insert({ bone, std::set<short>{ trivert_index }});
         else
             bone_triverts[bone].insert(trivert_index);
     };
@@ -681,7 +681,7 @@ void HL1MDLLoader::read_meshes() {
         short new_trivert_index = static_cast<short>(triverts.size());
 
         if (triverts_similars.count(trivert.vertindex) == 0)
-            triverts_similars.insert_or_assign(trivert.vertindex, std::set<short>{ new_trivert_index });
+            triverts_similars.insert({ trivert.vertindex, std::set<short>{ new_trivert_index }});
         else
             triverts_similars[trivert.vertindex].insert(new_trivert_index);
 

code/MDL/HalfLife/UniqueNameGenerator.cpp

@@ -146,7 +146,7 @@ void UniqueNameGenerator::make_unique(std::vector<std::string> &names) {
 
         // Map each unique name to it's duplicate.
         if (names_to_duplicates.count(names[i]) == 0)
-            names_to_duplicates.insert_or_assign(names[i], DuplicateInfo());
+            names_to_duplicates.insert({ names[i], DuplicateInfo()});
         else
             names_to_duplicates[names[i]].indices.push_back(i);
     }