line: quantity_balance, validate,

reconciliation: start/end-quantity
todo: tests

__init__.py

@@ -7,10 +7,12 @@ from trytond.pool import Pool
 from .types import Type
 from .book import Book
 from .line import Line
+from .reconciliation import Reconciliation
 
 def register():
     Pool.register(
         Type,
         Book,
         Line,
+        Reconciliation,
         module='cashbook_investment', type_='model')