Implemented some enhancement request and fixed some bugs

Fixed #2 : Variables are not recognized when inside a rule token
Fixed #15 : Rule: rete attributes are lost when a new ontology is created
Fixed #14 : ReteNetwork: Format rules must not be added to Rete network
Fixed #16 : DefConcept: Variables are not recognized when they are keyword arguments
Fixed #4 : Comparison are not correctly set when comparison property is a concept
Fixed #14 : Parser: merge FunctionParser.NamesNode and ExpressionParser.NamesNode
Fixed #18 : Parser: Add SourceCodeNode test to UnrecognizedNodeParser
Fixed #20 : At startup Number concept is saved in db a numerous number of time
Fixed #21 : CacheManager: I can remove all elements from a ListIfNeededCache and fill it again
Fixed #22 : CacheManager: I can remove all elements from a SetCache and fill it again
Fixed #23 : HistoryManager: history() no longer works
Fixed #24 : HistoryManager: history() no longer works after creating an exec rule
Fixed #25 : SheerkaMemory: Use MemoryObject instead of sheerka.local
Fixed #26 : Debugger: add the list all available services..
Fixed #27 : CONCEPTS_GRAMMARS_ENTRY does not seems to be in use any more
Fixed #28 : Give order to services

tests/core/test_SheerkaIsAManager.py

@@ -1,5 +1,3 @@
-import pytest
-
 from core.builtin_concepts import BuiltinConcepts
 from core.concept import Concept
 from core.sheerka.services.SheerkaIsAManager import SheerkaIsAManager
@@ -278,7 +276,7 @@ class TestSheerkaIsAManager(TestUsingMemoryBasedSheerka):
         assert [c.id for c in concepts_in_cache] == [one.id]
 
         # pretend that number has been updated in sheerka.concepts_grammar
-        sheerka.concepts_grammars.put(number.id, "some parsing expression with 'one' only")
+        sheerka.get_concepts_bnf_definitions().put(number.id, "some parsing expression with 'one' only")
 
         # add another element to number
         sheerka.set_isa(context, sheerka.new("two"), number)
@@ -289,7 +287,7 @@ class TestSheerkaIsAManager(TestUsingMemoryBasedSheerka):
         assert {c.id for c in concepts_in_cache} == {one.id, two.id}
 
         # make sure the bnf definition is also updated
-        assert number.id not in sheerka.concepts_grammars
+        assert number.id not in sheerka.get_concepts_bnf_definitions()
 
     def test_i_can_get_and_set_isa_when_multiple_ontology_layers(self):
         sheerka, context, foo, group1, group2 = self.init_concepts(