Extended Exploration Resources

Reworks Exploration age resources for more variety: - Salt and Wool carry over from the Antiquity age and remain present in the Exploration age. - Ivory, Marble, Truffles, and Wine are now Treasure Resources. I always found it odd that Salt and Wool disappear so early, given how central they were to medieval economies. Together, they formed the economic foundation of the rise of northwestern global empires such as the Netherlands and England / Britain. Now they stick around for a bit longer. Since Update 1. 2 made Treasure Resources effectively work as Empire Resources on the side, these have become more interchangeable. However, many players report Treasure Resources spawning rather infrequently. Hopefully, allowing more Empire Eesources to function as Treasure Resources will counter that issue a bit. Wine already has a bonus analogue to a Treasure Resource (Fur), so I did not change its effect. Truffles (its unit production bonus moved back to Salt) now works similarly, giving Happiness in the capital and a percentage yield bonus when in a celebration, +10% Food in this case. Ivory and Marble are back to their antiquity effects of terrain-based wonder construction bonuses. I am not too fond of those, but reworking bonuses I just don't like wasn't the goal of this mod, any should any mod rework that in general, I will add compatibility to extend those new effects into the Exploration age, too.