Automate transactional SuMSy transfers in SuMSyBalance

[stefkuypers]

If a SuMSyBalance is transactional, all transfers between that balance and others should automatically recalculate the balance entry value based on SuMSy settings.

The challenge is to notify the caller that guaranteed income and demurrage has been applied, and to what they amount. This is necessary for data gathering in simulations.