account print balance dependant of sign

for balance purpose it is necessary (in Austria) to evaluate the balance of an account (bank) or a group of accounts (same bank many accounts or VAT and other accounts of financial authorities) before printing.

these accounts are usually defined as general ledger.

an account (or view) can be defined as
* print (regardles of balance)
* print only debit balance
* print only credit balance

obviously if balance is to be checked the account has to be defined twice in the structure.

settings for views override settings of accounts, meaning that if the parent view balance is debit then all accounts have to printed regardless of their individual balance. (same for credit)