Remove unused coin attributes from finalclass and warpclass

Looks like coins were basically a scrapped mechanic, although I'm not
sure what these attributes were for. I guess counting the number of
coins in each room? But why, when you can just make a function to count
them automatically? Whatever.

desktop_version/src/WarpClass.cpp

@@ -13,7 +13,6 @@ const int* warpclass::loadlevel(int rx, int ry)
 
 	t = rx + (ry * 100);
 	const int* result;
-	coin = 0;
 	rcol = 0;
 	warpx = false;
 	warpy = false;