fix 582b5e0ae6469d8db1a6d66efd47747ff444edea

Signed-off-by: Oleg Verych <olecom@gmail.com>
api.lftp.on(): API setup, handling by object; test callback

* api_load: override callback in succesive `api.lftp.on('mode', cb)`
* cnl: example of callback `test_api_lftp_on()`
* update comments
* farsh: add recv to lftp_loop(), add logic in lftp_recv*()
* sh.stdout.on('data'): close `dir` to pass it into various
  channel's callbacks

* 'wes4store error' messages are handled by:
  https://github.com/suprojs/supro/commit/42a68784c3c9cdd8dd8ad2b92a4cc6f032fe1b6e

Signed-off-by: Oleg Verych <olecom@gmail.com>