Generates an array of probabilities mapping the calibration curve and its error ribbon.
Each column represents a Gaussian PDF constructed from the C14 date and error of the calibration curve (typically a column every 5 cal years).
Row names of CalArray are 14C dates, column names are cal dates.
This function is memory and time costly if used to construct the entire 50,000 year range of the calibration curve at a resolution of 1 cal years, therefore typically used only for a constrained date range, by specifying calrange.
This array only needs constructing once to generate a Summed Probability Distribution of any number of calibrated dates, allowing efficient downstream calibration.