Fixed instant crash in last commit by adding valid testdata.yml, and fixed testdata.yml parsing.

testing/testdata.yml

@@ -0,0 +1,19 @@
+%YAML 1.2
+---
+title: Sample Text
+openingText: "{}\nsample text"
+startLevel: testing/test1.yml
+singletons:
+  - !NPC
+    name: follower
+    description: a follower
+    location: [0, 0]
+    behaviors:
+        go: [-1, follow]
+        arrive: [-1, follow]
+    customValues:
+        follow:
+            distance: 2
+            isFollowing: True
+            target: You
+