Various Item pool fixes

* Pedestal goal always left a spare item in the pool, unless vanilla swords was also selected
* extra items for the pool can now be given dynamically based on items still needed.
* easy item pool + swordless gets 4 bows, not 2 (weird combo, but ok)
* add some item pool unittests
* add easy item pool to CLI and GUI

test/items/TestDifficulty.py

@@ -0,0 +1,47 @@
+from ItemList import difficulties
+from test.TestBase import TestBase
+
+base_items = 43
+extra_counts = (15, 15, 10, 5, 25)
+
+
+class TestDifficulty(TestBase):
+    pass
+
+
+def build_difficulty_test(difficulty):
+    # binds difficulty to definition local scope
+    def build_for(function):
+        def wrapped(self, *args):
+            return function(self, difficulty, *args)
+
+        return wrapped
+
+    return build_for
+
+
+def build_dynamic_tests():
+    for name, difficulty in difficulties.items():
+
+        @build_difficulty_test(difficulty)
+        def test_dyn_difficulty(self, difficulty):
+            base = len(difficulty.baseitems)
+            self.assertEqual(base, base_items)
+
+        setattr(TestDifficulty, f"testCountBase{name}", test_dyn_difficulty)
+
+        @build_difficulty_test(difficulty)
+        def test_dyn_difficulty(self, difficulty):
+            self.assertEqual(len(extra_counts), len(difficulty.extras))
+
+        setattr(TestDifficulty, f"testCountExtra{name}", test_dyn_difficulty)
+
+        @build_difficulty_test(difficulty)
+        def test_dyn_difficulty(self, difficulty):
+            for i, extras in enumerate(extra_counts):
+                self.assertEqual(extras, len(difficulty.extras[i]))
+
+        setattr(TestDifficulty, f"testCountExtras{name}", test_dyn_difficulty)
+
+
+build_dynamic_tests()