Refactor screen layout code, start player progress code

src/engine/datatypes.ts

@@ -91,6 +91,10 @@ export class Rect {
     this.size = size;
   }
 
+  offset(offset: Point) {
+    return new Rect(this.top.offset(offset), this.size);
+  }
+
   contains(other: Point) {
     return (other.x >= this.top.x && other.y >= this.top.y && other.x < this.top.x + this.size.w && other.y < this.top.y + this.size.h);
   }
@@ -186,5 +190,5 @@ export enum AlignX {
 export enum AlignY {
   Top = 0,
   Middle = 1,
-  Right = 2,
+  Bottom = 2,
 }