direction, x_coords, y_coords, bar_lengths, terminal_size
Plot an array of error bars in a given direction.

PARAMETERS
----------
direction     -    direction to plot the error bar relative to
                   the data point:

                     One-sided error bar:
                       DIR is 1 for +X (X to X+E);
                              2 for +Y (Y to Y+E);
                              3 for -X (X to X-E);
                              4 for -Y (Y to Y-E).
                     Two-sided error bar:
                       DIR is 5 for +/-X (X-E to X+E); 
                              6 for +/-Y (Y-E to Y+E).

x_coords      -    The X-axis coordinates of each error bar.

y_coords      -    The Y-axis coordinates of each error bar.

bar_lengths   -    The lengths of each error bar.

terminal_size -    (Optional: default=1)
                   The height of the error-bar terminals relative to
                   their default height.

Note that if the three coordinate arrays contain differing numbers of
elements, the smallest array will dictate the number of error bars
drawn.