YafaRay plugin; update roadmap and change list

[micheus]

I was using an object with vertex color settings and I noticed that maybe it was not implemented too.
So, I decided to use the option Vertex Attributes -> Color to Materials that produced a lot of materials. Change the parameters for each one of these materials would be a hard task.

That said, it would be useful add the options to set the default parameters for the default material we can set on Edit->Plug-in Preferences.