Fixed missing translation strings on loading campaign save

- campaign header now contains text container and stores campaign texts
- map header now contains text container instead of inheriting it
- moved text container registration logic to a wraper class
- fixed registration of copied text containers (from copied map header)

lib/CGeneralTextHandler.cpp

@@ -264,11 +264,14 @@ void TextLocalizationContainer::registerStringOverride(const std::string & modCo
 
 void TextLocalizationContainer::addSubContainer(const TextLocalizationContainer & container)
 {
+	assert(!vstd::contains(subContainers, &container));
 	subContainers.push_back(&container);
 }
 
 void TextLocalizationContainer::removeSubContainer(const TextLocalizationContainer & container)
 {
+	assert(vstd::contains(subContainers, &container));
+
 	subContainers.erase(std::remove(subContainers.begin(), subContainers.end(), &container), subContainers.end());
 }
 
@@ -414,6 +417,28 @@ void TextLocalizationContainer::jsonSerialize(JsonNode & dest) const
 	}
 }
 
+TextContainerRegistrable::TextContainerRegistrable()
+{
+	VLC->generaltexth->addSubContainer(*this);
+}
+
+TextContainerRegistrable::~TextContainerRegistrable()
+{
+	VLC->generaltexth->removeSubContainer(*this);
+}
+
+TextContainerRegistrable::TextContainerRegistrable(const TextContainerRegistrable & other)
+	: TextLocalizationContainer(other)
+{
+	VLC->generaltexth->addSubContainer(*this);
+}
+
+TextContainerRegistrable::TextContainerRegistrable(TextContainerRegistrable && other) noexcept
+	:TextLocalizationContainer(other)
+{
+	VLC->generaltexth->addSubContainer(*this);
+}
+
 void CGeneralTextHandler::readToVector(const std::string & sourceID, const std::string & sourceName)
 {
 	CLegacyConfigParser parser(TextPath::builtin(sourceName));