Eager mirror synchronisation.
Cosmetic / clearer.
Log progress, and an important optimisation.
Flow control for the sync process.
Oops
Merge bug25303
Fix expiry
Add spec, fix API, refuse to run if there are pending acks, return status, don't throw away state.
Cosmetic
Fix bugs in previous commit, and be rather more thorough about monitoring and cleaning up credit flow.
Send the sync_start over GM to flush out any other messages that we might have sent that way already.
Improve progfess logging.
Merge in default
React to memory monitor and FHC messages.
Don't hang on shutdown
Move the sync stuff to its own module
Handle update_ram_duration correctly.
simplify errors
merge default into bug24407
...which involved a minor tweak since #message_properties.delivered is
gone
Various QA cleanups