Mark OLESEN authored Oct 11, 2022 and Andrew Heather committed Nov 24, 2022

Changes / Improvements

- more consistent subsetting, interface

  * Extend the use of subset and non-subset collections with uniform
    internal getters to ensure that the subset/non-subset versions
    are robustly handled.

  * operator[](label) and objectIndex(label) for standardized access
    to the underlying item, or the original index, regardless of
    subsetting or not.

  * centres() and centre(label) for representative point cloud
    information.

  * nDim() returns the object dimensionality (0: point, 1: line, etc)
    these can be used to determine how 'fat' each shape may be
    and whether bounds(labelList) may contribute any useful information.

  * bounds(labelList) to return the full bound box required for
    specific items. Eg, the overall bounds for various 3D cells.

- easier construction of non-caching versions. The bounding boxes are
  rarely cached, so simpler constructors without the caching bool
  are provided.

- expose findNearest (bound...