find() with a closure

See #31, release log:

• 11a28f0 by @yegor256: typo
• 6d0fa3c by @yegor256: find() is now using find_with_...
• 54e9a1c by @UARTman: #31: implement `finds_with_clo...
• 5185b25 by @UARTman: fix redundant cloning in `Sodg...
• 2e9a0c7 by @UARTman: #31: implement `find_with_clos...
• df7b905 by @yegor256: #34 extra check
• f864d17 by @yegor256: #34 overwriting with tail
• 9cf640a by @yegor256: #33 return a and tail from kid...
• e9ca8d9 by @yegor256: #32 check for label names
• 93b0c68 by @yegor256: rename
• 8deef0a by @yegor256: doc
• 626552b by @UARTman: #28: refactor type declaration...
• a404d42 by @UARTman: #18: revamp Hex

Released by Rultor 2.0-SNAPSHOT, see build log