E.g.	Default DPI:	For comparison, this is master:

Couple of reasons for this:

• Makes it easier to understand that and how these buttons map to nodes.
• These buttons represent node inputs, so it makes more sense to have the icons on the left.
• We'd like to show the usual decorators on the right, but having two circles for different purposes next to each other would be confusing.

Also respects the socket shape. So if a diamond shape is used for example, the
properties show that too.

I'm not sure if the previous icon textures were cached, either way this method
uses immediate mode drawing (reusing the existing drawing code, so it draws
one point per icon and does the rest in shaders). So this adds a draw call for
every socket icon which is a bit annoying, but probably neglectable. Would be
better if we'd use proper icon textures or batches, but that's a separate
change.