v1.0.19

• Fixes bug where incorrect market value was being calculated if bar dates were not shared by multiple symbols (#7)
• Changes PnL in TestResult#portfolio to be running total of realized + unrealized PnL. Removes unrealized_pnl column.
• Adds unrealized_pnl to EvalMetrics.
• Adds better error messaging if "predict" method is not found on a trained model instance when running predictions.
• Updates the project's license to Apache 2.0 with Commons Clause. PyBroker is free for non-commercial use.