Various little changes.


ChangelogDB.java:
Updated javadoc for getCSNAfter().


CSNGenerator.java
Added newCSNs(int) to generate a certain number of CSNs in one go. It is very useful in tests.

CSNGeneratorTest.java
Added a test for newCSNs(int).

ReplicationServer.java:
In getChangelogDB(), weakened visibility from private to default for unit tests access.

JEChangelogDB.java:
In getOrCreateDbHandler(), weakened visibility from private to default for unit tests access.

DbHandlerTest.java:
Cleaned up the tests by relying on production code methods cleanups.
Used CSNGenerator(.newCSNs().
Added newDbHandler(), testGenerateCursorFrom().
Renamed/inlined a few local variables.

DraftCNDbHandlerTest.java:
Cleaned up the tests by relying on production code methods cleanups.
Used CSNGenerator(.newCSNs().
Added newDbHandler().


PendingChange.java, ExternalChangeLogTest.java:
Renamed "changeNumber" to "csn".