Fixed #43 : BnfNodeParser: I can recognize when multiple level of ISA

Fixed #44 : BnfNodeParser: I must simplify results when multiple levels of ISA
Fixed #45 : Dynamic variables cannot be parsed at restart
Fixed #46 : Concepts variables values are transformed into list by default
Fixed #47 : SheerkaAdmin. Add min, max, mean time when restoring files

tests/core/test_utils.py

@@ -386,8 +386,10 @@ def test_i_can_deep_copy_a_concept():
                        desc="concept2_desc",
                        id="concept2_ids",
                        props={"prop_name": concept1},
-                       variables=[("var1", "default_value1"), ("var2", "default_value2")],
+                       variables=[("var21", "default_value21"), ("var22", "default_value22")],
                        bound_body="var1")
+    concept2.set_value("var21", "default_value21")
+    concept2.set_value("var22", "default_value22")
 
     concept = Concept(name="my_name",
                       is_builtin=True,