add 'source' property

src/content/ContentPack.cpp

@@ -88,6 +88,7 @@ ContentPack ContentPack::read(const fs::path& folder) {
         root.at("creator").get(pack.creator);
     }
     root.at("description").get(pack.description);
+    root.at("source").get(pack.source);
     pack.folder = folder;
 
     if (auto found = root.at("dependencies")) {

src/content/ContentPack.hpp

@@ -42,6 +42,7 @@ struct ContentPack {
     std::string version = "0.0";
     std::string creator = "";
     std::string description = "no description";
+    std::string source = "";
     fs::path folder;
     std::vector<DependencyPack> dependencies;