4.3.0

Standalone builds should not require installation of .NET Core 3.1 (feedback welcome). The other packages expect .NET Core 3.1 to be installed. Both require this support system, but standalone packages include the libraries.

- Multiple refinements to the raycaster, keyholer and boolean systems.
 - Exposed ray extension in the ILB UI.
- Viewport context menu now shows hotkeys.
- Proximity bias revised to allow customizable falloff to be applied to side rays.
 - Previously, all rays were given equal weight and this caused a reduction in the visibility effect for a number of cases.
 - Now, there is a customizable falloff option (None, Linear, Gaussian, Cosine). The effect can also be amplified with a multiplier.
 - Result is a weighted average.
- DesignLibs enhancements for flattening of nested layout.
- Context menu for layer list box. Allows various convenient actions.
- Message boxes for confirmation when clearing a layer or resetting the tool.
- Layer-related elements (e.g. correlation / reference controls) now update to show the layer name, to ease understanding.