pngbehave 6.x-1.3

- using a blank sizingMethod removes the ability to define height and width on PNG images
Attempt to fix this by detecting defined sizes and setting sizingMethod to 'scale'.

- 'scale' sizingMethod still includes padding size in the total height/width
Correct this by subtracting the padding from the size before the image is scaled.

- Adding padding style to images and backgrounds will no longer break layouts

Issue discoverd: here
drupal.org issue #342582: Version 1.2 breaks defined sizes on PNG images

CHANGELOG.txt has been committed