T3 3 Averages

This function is an Pine version of the moving average described in
the January, 1998 issue of S&C magazine, p.57, "Smoothing Techniques
for More Accurate Signals", by Tim Tillson. It is translated from the
MetaStock code presented in the article. The function uses a version
of the XAverage, written by me, which allows variables as inputs.

The most popular method of interpreting a moving average is to compare
the relationship between a moving average of the security's price with
the security's price itself (or between several moving averages).