Bug 707354 - Bump Map offsets only go to 1000 regardless of image size

Allow ranges from -10000 to 10000, still arbitrary but more
real-world. The scales still go -1000 to 1000, but the spinbuttons
allow for the full range.

(cherry picked from commit af0cfacfb3fdd4308dc28167a8be74e5141fc1eb)