Add an option on the TaleSpire_Object node to set the footprint of an object when scattering.

[Baldrax]

When scattering objects of various size it would be nice if other objects were aware of how far they should keep away by allowing the footprint to be set per object.

[Baldrax]

Partial support was added for this in v0.23.0-alpha from this commit: 5e66f61

The Houdini scatter node that the TaleSpire_Scatter node is based off of does not support per item footprints at scatter time, these are only used when feeding existing scattered points into the scatter node to keep new ones away from the old ones.
So for now, that is what this does.

There is a new parameter on the TaleSpire_Object node called "footprint" which allows setting this distance and a circle in the viewport represents that radius.

In order to fully implement this feature a complete rewrite of how scattering works will need to be done. Before attempting that I would like to switch development to the latest build of Houdini (20.5 at the time of writing this) to see if there are any new features in Houdini that might make this easier.