Candle Convenience Functions

[khazaddim]

For when this is connected to a data source i will need a couple convenience functions:

1. ability to append a candle to the end of the series
2. ability to modify the last candle in a series. This will be needed for streaming or polling quotes so the candle can be updated before it is finished. This way stop losses can trigger off the candle before it is complete, if desired.

I will also need to generally need to review how series are loaded. I think i can have more than one series of candles at a time.