More Artifacts and Relics

While working on one of my Great People mods, I started adding extra Relics, and then extra Artifacts - and got a bit carried away. I've now moved these all in to their own stand-alone mod so that they are easier to use if you want. This mod currently adds 35 new Artifacts and 15 new Relics in to the game. IMPORTANT - GreatWorkShowcase.lua and GreatWorksOverview.lua had some hardcoded logic in them that used a fixed constant number of Artifacts and Relics. I've changed these to work around these limits. As a result, these changes will conflict with any other mods that also update these two LUA files. Without my changes both the Great Works overview and Showcase pop-ups WILL NOT OPEN.