Start replication from the last dump

Currently, replication slave needs to be manually "seeded" with a snapshot to be able to read .xlog files from the master. If the snapshot is not too recent, and some .xlog files created after this snapshot was taken are missing on the master, replication won't work.
The "seeding" is copying (via "scp", "ftp" or alike) the snapshot from the master.

From system administration point of view, it would be nice to be able to create a new replica by simply initializing it and pointing at the master. The master should be able to find the most recent snapshot automatically, feed it to the replica, and then continue with subsequent .xlog files.

There is another use case, when replica's .xlog file already contains records, but the master is missing .xlog files necessary to bring the replica up to date. Since there is no way to find out whether or not the data in the .xlog files on the replica corresponds to the data on the master, this case will need to be addressed by a separate task.