previous_image_link and next_image_link broken following a recent change

[johnconners]

[9774] has inadvertantly broken the underlying call to 'adjacent_image_link'. The test:

is_integer($q['post_parent'])

added in [9774] fails when it should succeed following the call to 'get_children' which passes 'post_parent' => $post->post_parent (and ultimately calls get_posts where the change was made). What appears to be happening is that in this case $post->post_parent is numeric, but is not an integer (so probably a string - there must be an int cast missing where it's set).

The easy fix is attached (change is_integer to is_numeric). It's either that or trawl through the code looking for where post_parent isn't cast to an int, thought I'd take the less dangerous (minimal code change) approach.

[ryan]

(In [9795]) Use is_numeric instead of is_integer. Props johnconners. fixes #8284