Threshold crossing deletion

Threshold crossing deletion: deletes (makes nan) all bar the max value for every group of consecutive values over a threshold.

Easily editable for actual deletion instead of making nan, or for getting min of each group etc etc...

% thresh_cross_del - for every group of consecutive values over a threshold, all but the max in the group are deleted (made nan)

%

% Inputs:

% var - data for the calculation

% threshold - threshold to calculate groups from

%

% Outputs:

% var_tcd - variable with group data deleted bar the max values