First beta of the nodeeditor :)

Main change:
- The Frame and Point types replaced with the PointArray type. This new type supports 3d arrays of points. For each point you can set x-y-z coordinates, three rotation angles, scale.

Other changes:
Added powerful Math nodes (Basic/Math and Arrays/GenArray)

Now you can add and remove optional input/output slots (right click on a node title to add slot, right click on a slot to remove it)

More intelligent selection tools
You can use shift+left mouse button or middle mouse button to select multiple nodes. Now you can easily move them around. Multiple delete doesn't work at the moment.
Slider and Knob nodes doesn't steal focus anymore when you use them.

You can use mouse wheel to zoom in and out

Added math support for property input fields. For example, you can set variables: a: -pi, radius: 2*pi+10 etc

Visual bugs fixed