Re-implement message wrappers

With the latest release we have changed the format of the adapters. In this new format we removed the command interpreter wrappers given that they were implemented in a fairly clunky manner and were not yet used by anybody. They were created to support the development of a simulated PMAC device, which has since been dropped in priority.

I am using this issue to collate references to the work done and that was left outstanding for the wrappers. The goal is to re-implement them within the new format when the demand is there.

**Merged:**
PRs:
- #80
- #82
- #89

**Not completed:**

Issues:
- #92
- #93
- #84

PRs:
- #90
- #91
- #94