* reworked and used TrsrDB::expand_ids more tightly
* account item selection in TrsrDB::make_transfers
* web_auth / User relation for coming HTTP interface
* income and target inter-relations between TrsrDB::Credit and TrsrDB::Debit
* Transfer note
* reactivated enforceFixedCredit to take effect unless _temp table is empty
* added CreditsInFocus and Report views
Renamed "debts" to "arrears", because of psychologically slightly more positive
connotations. Renamed field "Id" of table Credit to "credId" in analogy to
field "billId" of table Debit.
