Money Flow Index

Introduction
The Money Flow Index is a running indicator that measure trend strength and warns of likely reversal points.

Construction

 * 1) Calculate the typical price for each period, ie (period.high+period.low+period.close)/3
 * 2) Calculate Money Flow for each period, t [p] * volume
 * 3) Decide on time frame over which to calculate the index. This should be based on the cycle you are trading
 * 4) Calculate NegMoneyFlow: E (t[p] > 0) within the time frame
 * 5) Calculate PosMoneyFlow: E (t[p] < 0) within the time frame
 * 6) Calculate MoneyRation = +ve flow / -ve flow
 * 7) MFI = 100 - 100 / (1 + MoneyRatio)