Use rounding in ImageOps contain() and pad()

[bibinhashley]

Fixes ImageOps.contain function

Changes proposed in this pull request:

I tried to use ImageOps.pad on an image of size (4307, 6030) and I needed to resize it to (50,70). The image was resized but it had extended only on the right side. But actually, these two sizes don't need any expansion since both sizes are proportional.

So I checked the pillow code and found that ImageOps.pad is using ImageOps.contain and in contain function there is a code for calculating new height or new width based on the size.
new_height = int(image.height / image.width * size[0])
or
new_width = int(image.width / image.height * size[1])

But the problem here is when I ran that function with (50,70), it gave output (49,70).
code explanation:

size = (4307,6030)
new_width = int(image.width / image.height * size[1])
new_width = int(4307 / 6030 * 70)
new_width = 49

Expected output :

new_width = 50

But the new width should have been 50. So I changed " int " method with "round"

[radarhere]

I've created bibinhashley#1 to suggest a test, and to also use round() instead of int() in ImageOps.pad().

[radarhere]

@bibinhashley I find it slightly odd that you liked my comment, but haven't made any response to my pull request itself.

If you're taking a moment to review my suggestions, not to worry, but in case you're not familiar with this procedure - the intention is for you to look at bibinhashley#1, and if you're ok with my ideas, merge it. Those changes will then become a part of this PR.

[bibinhashley]

Sorry I was busy and I couldn't follow the procedure. I will check the test and merge it.

[hugovk]

Thank you both for the PR!