add basic types and fix cmake

src/lib/core/Rotation.h

@@ -0,0 +1,12 @@
+#pragma once
+
+// Rotation applied to a building's surface_mask when placed. Also the direction
+// of an output port or belt flow.
+// North = -Y (up), East = +X (right), South = +Y (down), West = -X (left).
+enum class Rotation
+{
+    North,
+    East,
+    South,
+    West,
+};