Allow PixelAccess to use Python __int__ when parsing x and y

[radarhere]

Resolves #5048

The issue reports that

px = im.load()
px[numpy.int32(5), numpy.int32(5)]

returns

TypeError: an integer is required

This PR calls __int__() on the object passed in, which should provide support for other kinds of objects as well.

[X-Bruce-Y]

Thank you for making life easier!

[wiredfool]

Do we need to do anything on PyAccess for this?

[radarhere]

Testing, I find that PyAccess works without this PR. The following code produces no error.

from PIL import Image
import numpy
Image.USE_CFFI_ACCESS = True
im = Image.open("Tests/images/hopper.png")
pix = im.load()
print(pix.__class__)  # <class 'PIL.PyAccess._PyAccess32_3'>
pix[numpy.int32(1), numpy.int32(2)]