Camera "up" vector is not properly used.

[derifatives]

When rendering a scene, everything looks fine with a camera position of (0., 1.5, -1.5). Changing the x-coordinate causes the csene to tilt, and using positive z's renders the scene upside-down.

[Qwlouse]

Reopening because #198 broke other usecases and a test, so I reverted it.

[Quasimondo]

Yes, I can confirm that this fix does not work as intended:

Here is an example where the camera is rotated 90° when using the fix, but correctly pointing up with the old version:

scene.camera.position = (6, 0, 3.0)
scene.camera.look_at((-0.5, 0, 2.0))

[MrXandbadas]

made a new function.
This is how I've tested it so far.
scene.camera.set_position((6, 0, 3.0))

It basically just updates the position and then grabs the "look_at" parameter and applies it again.
Haven't explored is in its entirety to ensure it doesn't break other things

@Qwlouse If you could let me know what other use cases it broke I'll happily attempt to test them xD