Additional balances to consider tracking in balance_tracker

Additional balances to consider tracking in balance_tracker:

• open orders
• unfinished escrow transfers
• pending conversions
• pending saving withdrawals

Those balances should be shown as well (as sums, so f.e. all orders to sell HIVE should be clumped together as one HIVE balance etc.). There should also be a total value as a sum of all assets of particular type. General idea is that asset should remain visible on user balance (and total should not change) until operation is finalized (so f.e. conversion from HBD to HIVE should remain as part of HBD in pending conversions balance until it triggers and becomes part of HIVE liquid balance). This way when user performs an operation on the asset, it just moves from one visible balance to the other until it changes to other asset or becomes part of some other user balance.