Do not load Markov name generator if a CFG generator could be loaded (#921)

name_generator_factory::add_name_generator_from_config now only falls
back to loading a Markov-chain generator if the loading of the context-
free grammar generator fails or there is none available.

src/utils/name_generator_factory.cpp

@@ -39,6 +39,7 @@ void name_generator_factory::add_name_generator_from_config(const config& config
 	if(config.has_attribute(cfg_name)) {
 		try {
 			name_generators_[id] = std::shared_ptr<name_generator>(new context_free_grammar_generator(config[cfg_name]));
+			return;
 		}
 		catch (const name_generator_invalid_exception& ex) {
 			lg::wml_error() << ex.what() << '\n';

src/utils/name_generator_factory.hpp

@@ -48,7 +48,8 @@ private:
 	std::map<std::string, std::shared_ptr<name_generator>> name_generators_;
 
 	/**
-	 * Determines a name generator from WML data
+	 * Determines a name generator from WML data. Tries first to load a context-free generator,
+	 * then falls back to Markov.
 	 * @param config the WML data to be parsed for name generators
 	 * @param the prefix to look for
 	 * @returns a name generator or nullptr if not found