XY_RASTER makes a mosaic of several images and prints the times in the corner
of each image. Sample calls are:
IDL> xy_raster, index, data
IDL> xy_raster, index, data, factor
where factor is the rebin factor (a value of 1 will perform no
rebinning). If there are too many images, the program will display
the number of images which will fit on a page, and will prompt the
user for when to move to the next page. The keyword /notimes will
inhibit the time labels, /noscale will inhibit image scaling (it will
use TV instead of TV_SCL), /individual_scale will scale each image
individually.