[validation] Remove default terminology check

The property_terminology_check validation can lead to a
threading lock in some cases when using Python 3.8 though
I was not able to figure out the details yet. Therefore
the validation is kept, but removed from the default
Validation checks until this can be resolved.

Also brings the docstring up to date and adjusts the
corresponding test.

Author: mpsonntag

odml/validation.py

@@ -451,9 +451,7 @@ def object_name_readable(obj):
 
 def property_terminology_check(prop):
     """
-    1. warn, if there are properties that do not occur in the terminology.
-    2. warn, if there are multiple values with different units or the unit does
-       not match the one in the terminology.
+    Tests if there are properties that do not occur in the terminology.
     """
     validation_id = IssueID.property_terminology_check
 
@@ -470,9 +468,6 @@ def property_terminology_check(prop):
         yield ValidationError(prop, msg, LABEL_WARNING, validation_id)
 
 
-Validation.register_handler('property', property_terminology_check)
-
-
 def property_dependency_check(prop):
     """
     Produces a warning if the dependency attribute refers to a non-existent attribute

test/test_validation.py

@@ -208,6 +208,9 @@ def test_uniques(self):
             """)
 
     def test_property_in_terminology(self):
+        odml.validation.Validation.register_handler("property",
+                                                    odml.validation.property_terminology_check)
+
         doc = samplefile.parse("""
             s1[t1]
             - P1