Hashing scheme for txs is buggy

[noel2004]

Currently the hashing scheme for txs, which is used as witness and signed by user's L2 key, still seems to be buggy. Like:

• In transfer and redraw tx, the hashed amount is divided by 1,000,000 (a hard coded magic number)
• Nonce is not really being hashed in redraw tx
• Old balance is planned to be involved in redraw tx, but I consider this is not a good idea because deposit and spotTrade both can change the current balance at any time and make the signed redraw tx invalided
• Witness of order input lack of any fields for prohibiting aggregator replaying them (like put one order to multiple open slots)