Do day 13 and add cleaner solution to day 18.

lib.py

@@ -133,7 +133,7 @@ class Input:
         return self.text.splitlines()
 
     def paras(self) -> list[list[str]]:
-        return [p.splitlines() for p in self.text.split("\n\n")]
+        return [p for p in self.text.split("\n\n")]
 
     def grid2(self) -> Grid2D:
         return Grid2D(self.text)