Port my fixes based on the patch from Matthias Basler from gramps34
[2eca30] 7290: use simpler math in image_dpi
[2f5e22] 7290: align warning with the image_dpi fix logic
[36f84e] 7290: image_dpi default calc based on gtk.gdk
[161ce3] 7290: ImgManip.image_dpi shouldn't return None
[460e63] 7288/7290 refactor out crop_percentage_to_pixel
[a8a38f] 7288/7290 refactor out crop_percentage_to_subpixel
[0d61bb] 7288/7290: refactor fix from matthiasbasler
[088146] rm relict RCS kwd
[76df5d] 7288/7290: image cropping fixes in ODFDoc
Using legacy gtk interface in image.py at the moment, need to port
to the new style.
Tested with python2.
37f4b411e3