introduce safe get python bindings to prevent deallocating none exception

[cagdasbas]

Although it's a python bug, returning too many none values causes python to crash irrecoverably. This is discussed and fix is introduced #1967. I've implemented for the fix for all of the possible Array typed values to prevent this issue.

[tc185187]

Yes, this is awesome. Fixed my problems completely, tricky bug to find with an easy fix. Clip it and ship it.

[yktangac]

Conclusion : datum.getPoseKeyPoints() return array with -1 (without ppl) return nx18x3 array (with ppl) Nice Work! Dude ! ^_^