refactor swait record support like calcout

[prjemian]

New support for the calcout record defines the fields with more descriptive names than current swaitRecord support. And the new support also uses a superclass for fields common to all record types. Time to refactor the swait record support to be consistent.

One aspect that will be improved is swait.channels.A.value.value will be replaced with something like swait.channels.A.input_value.value.

[prjemian]

API change? Bump major version number?

Note that since this change will break the current API for the swait record, should the major version number be incremented? This is not a major change for the apstools package, just this one smaller part of it. Just increment the patch number instead, as planned.