normalizeZScore - Z-score normalization
Normalizes the image time series as z-scores.
Description
This function normalizes image series with dimensions Y,X,T to have zero mean and unit standard deviation over the time domain. This function has no parameters.
Input
This function accepts only image time series as input with dimensions Y, X and T.
The algorithm
For each pixel, the z-score is calculated as the pixel value minus it's time average divided by the standard deviation.
Give the signal S(i,t), for each pixel i, the z-score is calculated as:
where Si(t) is the pixel value for a given time t, 
is the time average of the signal while the SD is the temporal standard deviation. The time average is calculated as:
and the standard deviation as:
Output
Image time series data with temporal mean equal to zero and unit standard deviation.