fix memory leaks + minor refactor

Sources/Voxelotl/main.swift

@@ -1,13 +1,9 @@
 import Darwin
 
-var rect = Rect(origin: .init(0, 0), size: .init(32, 32))
-rect.origin += Point(10, 10)
-
 let app = Application(
   delegate: Game(),
   configuration: ApplicationConfiguration(
-  width: 1280,
-  height: 720,
+  frame: Size(1280, 720),
   title: "Voxelotl Demo",
   flags: [ .resizable, .highDPI ],
   vsyncMode: .on(interval: 1)))