COLFIX: Fix Deferred Charge Columns in a CCD Image

COLFIX will attempt to fix deferred charge columns (or rows) under the assumption that they can be fixed by additive corrections. Under default operation, the routine finds the median of each column, and then generates corrections to each column such that they all have the same median. The median is selected is a super-median, of median of the the original column medians. A number of fixes are given for crowded images or those containing extended objects, where the median may be biased. The SPLINE option fits a spline to the column medians in an attempt to preserve and slow trends originally in the data. MAX sets an upper threshold to exclude bright pixels that may bias the median, and MODE attempts to revise the median by using the difference in value between the median and first quartile to exclude bright pixels in the last quartile.