Fix settings for custom control sensitivities

[valeriyvan]

Fix settings for custom control sensitivities:

• make text fields for sensitivities editable only in custom mode
• store values in settings on end of editing or on scene dismissal

This fixes crash - issue #25.

Despite the fix makes sense for me, settings screen seems to be or partially broken or not well thought:

• I don't see even attempt to persist custom settings in the code. Is it a bug? Or design decision?
• It should be a button to cancel all changes and return to values as they were when settings screen was open.

[valeriyvan]

I would, probably, contribute much more to this repo provided PR are reviewed a little bit faster.

[ataffanel]

Thanks! This is merged.

The settings screen could indeed be greatly improved, it was done a long time ago by an iOS dev. beginner (me).

Sorry for the long review time, I was preparing and travelling to FOSDEM and since we are not Mac user I have to have access to the office dev-mac to review iOS PRs. I think it would help greatly to have some CI in github actions. I will look at the possibility of setting that up. If you have any experience in setting up iOS build in github actions it would be great to have pointers.

[valeriyvan]

https://github.com/marketplace/actions/ios-build-action

[valeriyvan]

https://blog.eidinger.info/save-money-when-using-github-actions-for-ios-cicd