(core) A few tiny documentation tweaks.

Summary:
- Improve readability of documentation of CONTAINS.
- Add leading underscore to Record._get_encodable_row_ids() to hide from
  public docs, and avoid interfering with user fields.
- Fix up lint errors

Test Plan: No behavior changes

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3209

sandbox/grist/table.py

@@ -89,9 +89,10 @@ class UserTable(object):
     ```
 
     See [RecordSet](#recordset) for useful properties offered by the returned object.
-    
-    See [CONTAINS](#contains) for an example utilizing `UserTable.lookupRecords` to find records where
-   a field of a list type (such as `Choice List` or `Reference List`) contains the given value.
+
+    See [CONTAINS](#contains) for an example utilizing `UserTable.lookupRecords` to find records
+    where a field of a list type (such as `Choice List` or `Reference List`) contains the given
+    value.
     """
     return self.table.lookup_records(**field_value_pairs)
 
@@ -356,6 +357,7 @@ class Table(object):
     col_id = summary_table._summary_helper_col_id
     if self.has_column(col_id):
       # If type changed between Reference/ReferenceList, replace completely.
+      # pylint: disable=unidiomatic-typecheck
       if type(self.get_column(col_id).type_obj) != type(_updateSummary.grist_type):
         self.delete_column(self.get_column(col_id))
     col_obj = self._create_or_update_col(col_id, _updateSummary)