Code review comment for lp:~weedfreak/widelands/recycling_centre

From AI's point of view:
We will probably need new ai hint like 'is_recycling_centre' and the bulding will be built based on number of trainingsites and productionsites and only one per type will be allowed.

Alternatively: AI can build the site if there is at least one ware for each input on stock. As indication, that scrap ware is being produced. Providing that scrap ware is not included in starting wares....