sockshare: new full-featured module

Features:
- download (password)
- upload, remote upload (async possible), folder, password
- list
- delete
- probe

Fixes issue 553.
Fixes issue 957.
plowdel: add --longhelp command-line option
plowlist: add --longhelp command-line option
bash completion: add missing option --longhelp
docs (man pages): minor update

Changes:
plowdel.1: add "Miscellaneous options" subsection
plowup.1: add missing --folder common module option
plowdel: add captcha command-line switches

Some hosters have captcha during login process.

Added options:
--9kweu
--antigate
--captchabhood
--deathbycaptcha
--captchamethod
--captchaprogram

Documentation updated.