Relay can't modify SODG back

See #75, release log:

• 4818027 by @yegor256: shorter log
• 9b1ca66 by @yegor256: shorter log
• 70e7b56 by @yegor256: locator is never empty
• c401cd1 by @yegor256: doc fix
• 7747d8a by @yegor256: more doc
• 986f984 by @yegor256: doc polished
• 6b631c1 by @yegor256: doc polished
• 668963d by @yegor256: doc
• c5866df by @yegor256: better log

Released by Rultor 2.0-SNAPSHOT, see build log