ReplicationDbEnv.java:
Renamed:
- field stateDb to changelogStateDb.
- start() to initializeFromChangelogStateDB().
- putInStateDBIfNotExist() to putInChangelogStateDBIfNotExist()
- deleteFromStateDB() to deleteFromChangelogStateDB() + changed the signature.
In getOrAddDb(), reduced code clutter and removed useless comments.
Extracted methods kb(), mb(), toBytes(), buildGenIdKey(), buildServerIdKey(), buildGenIdData() for better readability.
Extracted method debug() to reduce code clutter.
Used static imports.

ReplicationServer.java:
Consequence of the rename of ReplicationDbEnv.start().