Rename variables and message types

[byeonggiljun]

Some variable names and message types need to be renamed.

This is a list of them.

• TimedMessage -> TaggedMessage
• logical time -> logical tag tag
• LogicalTimeComplete -> LogicalTagComplete
• TimeAdvanceGrant -> TagAdvanceGrant
• ProvisionalTimeAdvanceGrant -> ProvisionalTagAdvanceGrant
• FederatedApp -> Federate

Generate codes should also be modified moderately.

[lhstrh]

Actually, one should never use the term "logical tag" but just "tag" (which is equivalent to "logical time").