[SCL] Better Heikin Ashi

To display the Heikin Ashi candle direction on your normal chart, using this script is better than switching between layouts. It includes different display modes so that you can use it alongside other indicators without clashing visually (bar colour/plotted shapes/shapes on flip only), and alerts on changes in direction. Many scripts include some or other of these features; here I've included them all in one for flexibility. One feature that AFAIK is unique is the "predictive close", which shows you where the current candle needs to close in order to change the Heikin Ashi direction.

Heikin Ashi is a different method of calculating candlesticks. It has several advantages:
+ It can help to show the dominant trend in a smoother way than normal candles.
+ Flips in direction can show either trend reversal, or a pause and continuation, which can be a place to join a trend.
Disadvantages of using Heikin Ashi include:
+ Having to change to a different chart layout
+ Difficulties working directly with Heikin Ashi values, because the values of the Open, Low, High, and Close displayed are different to the "real" prices.
This indicator solves this problem by bringing trend information from Heikin Ashi candles (whether they're bullish or bearish) onto your normal candle chart. It displays in the main chart pane.