Update Plot Charts

[AlexCatarino]

Plot Charts should use api.read_live_chart to get the data:

import pandas as pd
qb = QuantBook()

series = api.read_live_chart(14988739, 'Strategy Equity',
    0, datetime.now().timestamp(), 100).chart.series

equity = {x.time:x.close for x in series['Equity'].values}
daily_performance = {datetime.fromtimestamp(x.x): x.y for x in series['Daily Performance'].values}
returns = {datetime.fromtimestamp(x.x): x.y for x in series['Return'].values}

Members should use 'Return', which provides daily updates, while 'Daily Performance' has as many datapoints as 'Equity',. 'Equity' may not be updated daily.