Blender Git Loki

UI: Use property split layout and decorators for material properties

Use the automatic property split layout (hence, change to the new 40/60% split
ratio) and add decorator buttons for animatable properties.
This actually applies to all node input buttons in the properties, e.g. world shading,
light shading, texture nodes.

Doing this makes the layout more consistent with other layouts in the
properties. But the decorators are also a useful hint for users that these
options can be animated. Previously using decorators and the automatic split
layout wasn't possible, I've done a number of changes now to have it supported.
Before I moved the socket icons to the left side, the decorators also looked
weird (two circle icons next to each other).

{F8497704} With nested items: {F8497708}

Reviewed By: William Reynish, Pablo Vazquez

Differential Revision: https://developer.blender.org/D7544