No fallback on visibility controls (other settings may not either) about hdblackbird

[boberfly]

Having a deep-dive if I could solve this one myself, for object/mesh/curve/volume/lights I can set the actual default value by hand from what cycles is set to, but it would be preferred to get the default value from the schema itself.

I also saw all of renderParam.cpp it is just feeding in the previous value as default value, which is wrong as it should be the default value that is set at init time (the default built into cycles values and not just the previous value which will change as the user changes values in a running session).

[boberfly]

Potential fix:
#151