Fix Chandelier Exit Formula

[henryrossiter]

Fixes formula errors in Chandelier Exit calculation.

Stockcharts defines Chandelier Exit as:

Chandelier Exit (long) = 22-day High - ATR(22) x 3 
Chandelier Exit (short) = 22-day Low + ATR(22) x 3

The same formula is shown here, here

Changes:

• Always use high and low columns to calculate rolling max and min
• Change - to + in short calculation
• Change default window in short calculation to 22 (Charles Le Beau recommended using a 22-day window and 22 is more commonly used than 14)

[peerchemist]

Please fix the unittest for Chandelier as well.