LAS voxelization hangs forever

Daniel Stefan Kükenbrink daniel.kuekenbrink@wsl.ch reported that some LAS voxelization hanged forever unexpectedly.

An analysis of the issue showed that the LasShotIterator generated and error when LAS point GPS time matches the upper bound of the trajectory, generating an ArrayIndexOutOfBoundsException that was never thrown.

Looking down at the code there is indeed some case where the call to queue.take() in the LasShotIterator may block forever, especially when an exception occurs and the thread dies.

It could be fixed by implementing a Poison Pill Pattern.