Tests for VHM Events classes

Tests for all classes concerning Vhm events.

ee/test/VhmEventReaderTestSyntaxError.json

+{
+  "vhm_events_version" : 1,
+  "event1" :
+    "type" : "DISASTER",
+    "event_range" : 300,
+    "location" : {
+      "x" : 1000,
+      "y" : 1000
+    }
+  }
+}
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