Refactor(English): Rename all files and identifiers from Dutch to English

Renamed files: constanten→constants, adt-positie→adt-position,
adt-doolhof→adt-maze, adt-sleutel→adt-key, adt-tijdslimiet→adt-timer,
adt-teken→adt-draw, adt-spel→adt-game. All message names, variables,
comments, and tests converted to English.

Also fixed counter location bug (time-label x/y were swapped).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pacman-project/tests/test-timer.rkt

@@ -0,0 +1,55 @@
+#lang r7rs
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;                           Tests: Timer ADT                                ;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define-library (pacman-project tests test-timer)
+  (import (scheme base)
+          (pp1 tests)
+          (pacman-project adt-timer))
+  (export test)
+
+  (begin
+
+    ;; Test initial time
+    (define (test-initial)
+      (define t (make-timer))
+      (check-eq? (t 'remaining-time) 60 "Initial time should be 60 seconds")
+      (check (not ((t 'time-up?))) "Time should not be up at start"))
+
+    ;; Test decrease after 1 second
+    (define (test-decrease)
+      (define t (make-timer))
+      ((t 'decrease!) 1000)
+      (check-eq? (t 'remaining-time) 59 "Time should be 59 after 1 second"))
+
+    ;; Test increase (coin bonus)
+    (define (test-increase)
+      (define t (make-timer))
+      ((t 'decrease!) 1000)
+      ((t 'increase!))
+      (check-eq? (t 'remaining-time) 60 "Time should be 60 after decrease + increase"))
+
+    ;; Test format-time
+    (define (test-format)
+      (define t (make-timer))
+      (check-eq? ((t 'format-time)) "1:00" "60 seconds = 1:00")
+      ((t 'decrease!) 1000)
+      (check-eq? ((t 'format-time)) "0:59" "59 seconds = 0:59"))
+
+    ;; Test time-up?
+    (define (test-time-up)
+      (define t (make-timer))
+      ;; Decrease 60 times by 1 second
+      (do ((i 0 (+ i 1)))
+        ((= i 60))
+        ((t 'decrease!) 1000))
+      (check ((t 'time-up?)) "Time should be up after 60 seconds"))
+
+    (define (test)
+      (run-test test-initial "Timer: initial time")
+      (run-test test-decrease "Timer: decrease")
+      (run-test test-increase "Timer: increase")
+      (run-test test-format "Timer: format-time")
+      (run-test test-time-up "Timer: time-up?"))))