Smaller bug fixes in the task gemtools.imcoadd.
The small differences have no implications for the reduction of the data. In the old version size of the derived masks was hard-wired to 1024 pixels x 1024 pixels. In the new version the required size is read from the headers of the input images. A bug that caused the task crash to if no objects were found has been fixed. Improved error trapping for unallowed parameters values.