For #25697 - deprecated `engine_init()` from the base Engine class.
This method has now been replaced with `pre_app_init()` which should be used instead.  `engine_init()` will still be called for backwards compatibility but will be fully removed in the future.
For #25697 - Fixed Tk dialog so that UI's aren't oversized in 3ds Max
Previously the layout of the widgets in the configuration panel would cause the minimum size of a Toolkit dialog to be too large!
Closes #88.