public CashFlowViewModel()
{
_contoData = new ContoData();
AddWithdrawCommand = new RelayCommand(AddWithdrawCommand_Executed);
AddCostCommand = new RelayCommand(AddCostCommand_Executed);
WithdrawDate = DateTime.Now;
CostDate = DateTime.Now;
SelfInvoices = new CollectionView(_contoData.CashFlowSelfInvoices());
Balance = _contoData.CashFlowBalance();
}
