Premise: When pose bones are selected, applying a pose library should
only affect the selected bones.
This commit fixes a bug where the pose was also applied when there was
no overlap between the selected bones and the bones in the pose. For
example, applying a pose which contains only keyframes for the left
hand, while only right-hand bones are selected, would apply the pose
to the left hand anyway.
The code is now also slightly more efficient; the removed 'selcount'
counter was only used as a binary (i.e. zero or non-zero). It's now
stored as a bitflag instead.
14e7ba0c8a