Request: balance --related

[rstacruz]

I'd like to quickly see where my Assets are going. One way to do this is:

# monthly breakdown of in & out of money
hledger bal Liabilities Income Expenses --monthly

Wouldn't a cleaner way be to do: bal Assets --related? That is, show me the balance for accounts that transfer in/out of Assets, based on transactions only involving Assets (like reg --related). This is better because:

• you don't see Liabilities → Expenses transactions (useful for, say, you bought a laptop with a credit card on 0% interest to be paid over 12 months).
• you don't see Income → Expenses transactions (useful for, say, not caring about deductions of your employer, but still being able to file them as expenses).

You can already do this via register --related, but that flag isn't available for balance.