Minimum separation for random patterns

[mattwthompson]

The random patterns should accept some sort of an argument that specifies a minimum distance as a constraint. From what I can tell, this sort of behavior is not supported in the random patters that exist.

As a simple example, functionalizing a given carbon atom in graphene more or less means an adjacent should not be available for functionalization. This could be avoided by using grid patterns, but that is physically undesirable for sense for some systems such as oxidized graphene.

[mattwthompson]

P.S. I don't think I have the permissions to apply labels, but somebody can label this as a feature request.

[summeraz]

I'm pretty sure I experimented with this locally several years ago. I'll see if I can find what I did (it might just be on an old branch), but either way this should be fairly easy to implement.