OrderBook and BtcEClient update

Please consider including my patches.

1. In OrderBook there was  bug with deleting completed orders. Not sure my revision is right, but it seems to work.
2. In BtcEClient an API call returns only 150 trades, which is useless in case you wish to calculate SMA/EMA for long period. I use API v3 instead v2 so that one can analyze up to 2000 trades.
3. In BtcEClient there was a minor bug with timestamps leading to API errors.