Small fixes

[coolteemf]

Projector couldn't actually be used without specifying device as several parts of the code relied on device for sensor dimensions and source to detector distance.
Instead, Projector now use its methods source_to_detector_distance and sensor_width, sensor_height, which default to device if device is set.
Also fix a wrong variable name for the logger in image_utils.py

[benjamindkilleen]

Thanks for the attention to this! However, this is the dev branch, which is always in development and subject to change. If you would like to add significant new features, please open a pull request to the main branch. You can also let us know if there's something you'd like to work on, and we'd be happy to discuss the best way to implement it.

[coolteemf]

Thank you for making the wonderful tool that is DeepDRR !
I understand that my changes may not integrate into the workflow of the dev team.
I just needed to use the dev branch in order to take advantage of the new cuda-python replacement for pycuda.
However, in order to be able to run my code, I needed to add those small fixes and I thought I would share these fixes.
If my changes are not needed, it is totally okay to just close the PR.

I'll let you know if I come across a feature I'd like to add to deepdrr !