Implement unique IDs and card linking

src/data/game.hpp

@@ -12,7 +12,7 @@
 #include <util/io/package.hpp>
 #include <script/scriptable.hpp>
 #include <script/dependency.hpp>
-#include <util/dynamic_arg.hpp>
+#include <util/dynamic_arg.hpp>
 
 DECLARE_POINTER_TYPE(Field);
 DECLARE_POINTER_TYPE(Style);
@@ -41,6 +41,7 @@ public:
   vector<FieldP>          set_fields;             ///< Fields for set information
   IndexMap<FieldP,StyleP> default_set_style;      ///< Default style for the set fields, because it is often the same
   vector<FieldP>          card_fields;            ///< Fields on each card
+  vector<String>          card_links;             ///< Possible links between cards
   OptionalScript          card_list_color_script; ///< Script that determines the color of items in the card list
   OptionalScript          import_script;          ///< Script applied as the last step of the new_card function
   vector<String>          json_paths;             ///< Paths inside JSON files to find the card array
@@ -50,8 +51,7 @@ public:
   vector<WordListP>       word_lists;             ///< Word lists for editing with a drop down list
   vector<AddCardsScriptP> add_cards_scripts;      ///< Scripts for adding multiple cards to the set
   vector<AutoReplaceP>    auto_replaces;          ///< Things to autoreplace in textboxes
-  map<String,String>      card_fields_alt_names;  ///< Other names that fields might go by, for example in CSV files
-
+  map<String,String>      card_fields_alt_names;  ///< Other names that fields might go by, for example in CSV files
   bool                    has_keywords;           ///< Does this game use keywords?
   OptionalScript          keyword_match_script;   ///< For the keyword editor
   vector<KeywordParamP>   keyword_parameter_types;///< Types of keyword parameters