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/parsers/test_FunctionParser.py

@@ -1,11 +1,10 @@
 import pytest
+
 from core.builtin_concepts import BuiltinConcepts
 from core.concept import Concept
-from core.rule import Rule
 from core.sheerka.services.SheerkaExecute import ParserInput
 from parsers.BaseNodeParser import SCN, SCWC, CN, UTN, CNC, RN
 from parsers.FunctionParser import FunctionParser, FN
-
 from tests.TestUsingMemoryBasedSheerka import TestUsingMemoryBasedSheerka
 from tests.parsers.parsers_utils import compute_expected_array