Version 2.8.5

• Calling saveTransform() with one argument now returns the serialised transform
  object, as intended, rather than producing an error.
• Comparisons between floating-point and enumeration types are now avoided when
  using the C++20 or later standard for compilation, since this now leads to a
  warning. (Reported by BDR.)
• The "Upgrading to RNiftyReg 2.x" section of the README has been removed, since
  the 2.x line of releases is now over 10 years old(!).