Bugs: contour_* routines

Bugs

The contour_* routines cannot be used if 'set_coord("world")'

The contour_* routines cannot be used if 'set_coord("world")' has been set in order to change the coordinate system of the Sherpa analysis session to the world coordinate system. The following ChIPS error results when any of the contour_* routines is called in this case (see the full list of contour routines by typing "contour*?" at the Sherpa prompt):

sherpa> set_coord("world")

sherpa> contour("data", "model", "fit", "resid")
chips ERROR: Data for contours must be regularly gridded

sherpa> contour_data()
chips ERROR: Data for contours must be regularly gridded

sherpa> contour_fit()
chips ERROR: Data for contours must be regularly gridded


sherpa> set_coord("physical")

sherpa> contour("data", "model", "fit", "resid")
sherpa> contour_data()
sherpa> contour_fit()

The image (logical) and physical coordinate system settings are unaffected by this bug.