Stop Flywheel BatchingEngine crash

[ByThePowerOfScience]

Check if Flywheel is using the instancing engine before asserting that it is. Since the Batching engine doesn't use an origin coordinate, I assume not having one shouldn't break anything, but you'll want to double-check.

Currently, attempting to use batching mode will crash the game immediately until the config is changed.

This patch also needs to be applied to the other branches as well.

Fixes #739 and #816.

[CLAassistant]

All committers have signed the CLA.

[ewoudje]

LGTM