Generalisation of packing style DiamondsPlus

[jdaw1]

The packing style DiamondsPlus could be more general. It assumes Three rows or columns (/Landscape or /Portrait), whereas this could be generalised to allow more.

However, likely as not, this doesn’t matter. Realistic use cases are for not more than twenty-something glasses. Maybe, and maybe not, a generalisation would give a slightly larger radius for 41 glasses. But for n ≤ 25, the current DiamondsPlus seems to be sufficiently general.