Use bone position as defined by the track

[centerionware]

io_tresjs doesn't necessarily export every bone into every animation track set so can no longer assume the bones position in the array is equal to h, so use the parent value from the track - which seems to always be set to bone_position_in_array-1 in io_three, and definitely is that in io_tresjs.

[centerionware]

I have to admit I am a little annoyed by this. Things were clearly designed to work this way - the way the patch makes it work - somebody took a shortcut while making the original, the exporter iothree does things this way for over a year but - bad feelings. Not evidence, not testing, but feelings,.. because feelings and not logic are obviously how this stuff works.