Add leading & trailing spaces to all operators in LefilteredQuery

Doing so forbids operators like << == =! in* etc..
The tests were updated

lodel/leapi/query.py

@@ -92,12 +92,12 @@ class LeFilteredQuery(LeQuery):
     
     ##@brief The available operators used in query definitions
     _query_operators = [
-                        '=',
-                        '<=',
-                        '>=',
-                        '!=',
-                        '<',
-                        '>',
+                        ' = ',
+                        ' <= ',
+                        ' >= ',
+                        ' != ',
+                        ' < ',
+                        ' > ',
                         ' in ',
                         ' not in ',
                         ' like ',

tests/leapi/query/test_filtere.py → tests/leapi/query/test_filtered.py

@@ -73,6 +73,9 @@ class LeFilteredQueryTestCase(unittest.TestCase):
                             "'",
                             "not_exists != bar",
                             "lodel_id # bar",
+                            "lodel_id == bar",
+                            "lodel_id =! bar",
+                            "lodel_id >> bar",
                             "lodel_id ind 42,43",
                             "lodel_id llike 42",
                             ('lodel_id', '', '42'),