Clean profiler data at the end of session run

reactor/Core/src/jetbrains/mps/logic/reactor/core/MemEvaluationSession.kt

@@ -60,6 +60,7 @@ class MemEvaluationSession : EvaluationSession {
             finally {
                 ourBackend.ourSession.set(null)
                 profiler?.formattedData()?.entries?.forEach { e -> durations?.put(e.key, e.value) }
+                profiler?.clear()
             }
 
             return session

reactor/Core/src/jetbrains/mps/logic/reactor/core/Profiler.kt

@@ -46,6 +46,10 @@ class Profiler {
         }.toMap()
     }
 
+    fun clear() {
+        tokenStack.clear()
+    }
+
 }
 
 class Token(val name: String, val id: Int) {