Convert read column into proper type with SQLite

As SQLite has few basic types, we must use column names cast parsing to ensure
to read values in proper type.

issue9652
review310801004

tests/scenario_product_cost_history.rst

@@ -104,10 +104,10 @@ Check cost history::
     >>> [c.cost_price for c in ProductCostHistory.find([], order=order)] == [
     ...     Decimal('100.0000'), Decimal('120.0000'), Decimal('110.0000')]
     True
-    >>> [str(c.date) for c in ProductCostHistory.find([], order=order)] == [
-    ...     str(today - dt.timedelta(days=2)),
-    ...     str(today - dt.timedelta(days=1)),
-    ...     str(today)]
+    >>> [c.date for c in ProductCostHistory.find([], order=order)] == [
+    ...     today - dt.timedelta(days=2),
+    ...     today - dt.timedelta(days=1),
+    ...     today]
     True
 
 Check cost price history on product::