Replace `myIbans` concept

[michielbdejong]

There are a number of steps from data sources to query result:

• import the raw data sources
• parse to AccountHistoryChunks in the case of bank statements, use the arms of the Y.
• add implied purchases
• parse incoming usage reports / invoices to AccountHistoryChunk(s)
• parse outgoing hours-reports / invoices to AccountHistoryChunk(s)
• parse budgets to AccountHistoryChunk(s)
• in the case of trackEquity for instance, sum it all up to see how hours-worked and other income increase equity and how purchases / expenses to budgets decrease equity each day.

I'm currently using dataRoot.myIbans for the list of bank accounts for which I have bank statements, but also as the list of accounts whose balance is mine to spend.

Need to clean that up!