More utility methods: one for creating a new image with the same configuration as another and one for computing a rectangle that bounds all non-transparent pixels in an image.
More utility methods: one for creating a new image with the same
configuration as another and one for computing a rectangle that bounds all
non-transparent pixels in an image.


git-svn-id: a1a4b28b82a3276cc491891159dd9963a0a72fae@1483 542714f4-19e9-0310-aa3c-eee0fc999fb1

threerings/narya,threerings/narya,threerings/narya,threerings/narya,threerings/narya