Scan for trinkets and put them into shinytrinkets in customs

For showtrinkets() to work, we'll need the correct map data in custom
levels.

desktop_version/src/Map.h

@@ -35,6 +35,7 @@ public:
     std::string getglitchname(int x, int y);
 
     void initmapdata();
+    void initcustommapdata();
 
     int finalat(int x, int y);