Spot light inner radius should always be smaller than outer radius

[mvaligursky]

At the moment these can be set up the other way around, and the light does not render correctly. We should prevent these from being able to be set incorrectly.

[albertvanveen]

I think this 'bug' can also be a 'feature' to create for exampe a 'shadow'.

[mvaligursky]

I think for that case a cookie texture should be used instead.
This is a bug as it breaks shadow mapping as well in a way.