Enables the character templates

They had been disabled for the mod manager as they might contain data that is only available with specific mods. If the template contains something that does not exist in the currently loaded world it is ignored (and some things print a debug message: missing professions, missing skills).
Traits/mutations are stored in a `std::set<std::string>`, that set might end up with some traits that do not exist in the current world, but this should not be a problem.