Shall we start using C++17 at the master branch?

[matt.mccormick]

@blowekamp

Another release candidate? I am not sure why actually releases are not occurring.

As was discussed with the last release candidate, there were a number of outstanding, critical contributions related to DICOM support that had not been integrated. These have now been integrated. 5.4 RC 3 will be the last release candidate.

@blowekamp

More specific to the point, I would expect the requirements for the next release (non-RC) to be set, and after the release the build requirements may change.

Yes, changes to build requirements should not be made until after v5.4.0.