Mark OLESEN authored Sep 28, 2023 and Andrew Heather committed Oct 11, 2023

- default construct is now identical to HashTable(Foam::zero).
  It performs no allocation and is also noexcept.

  The previously used default capacity (128) was a holdover from
  much older versions where set/insert did not properly handle
  insertion into a table with zero capacity (number of buckets).