cleaned up/improved message class comments more.
cleaned up/improved message class comments more.

Baaaaam/cyclus,hodger/cyclus,Baaaaam/cyclus,rwcarlsen/cyclus,mbmcgarry/cyclus,hodger/cyclus,Baaaaam/cyclus,mbmcgarry/cyclus,rwcarlsen/cyclus,hodger/cyclus,gidden/cyclus,gidden/cyclus,hodger/cyclus,rwcarlsen/cyclus,gidden/cyclus,mbmcgarry/cyclus,gidden/cyclus,hodger/cyclus,rwcarlsen/cyclus,mbmcgarry/cyclus