Add support for sampler settings to more types of textures.

[Oortonaut]

In particular, texture(3d), rt, image(3d), and cube maps. This includes min/mag settings and wrap settings as appropriate. Access the settings with the new "Sampler" subtree in the properties list.

Tested round trip load/save operation with Image3D and live updating of sampler settings. Desk checked for other types of objects.

This pipeline uses a compute shader to fill an Image3D with a gradient rgb = xyz. This pixel shader is sampling that texture along u, v, 0.5.

And with different sampling

[MaKiPL]

Checked the code and looks fine to me