[ticket/12393] Add poll options to hidden inputs

This will make sure that polls are not deleted upon quickediting a post.

PHPBB3-12393
[ticket/12393] Remove unneeded build_hidden_fields() from quickedit ajax part

PHPBB3-12393
[ticket/12393] Add return false to cancel button click event

This will ensure that the form is not submitted after clicking cancel.

PHPBB3-12393
[ticket/12393] Add docblock to quickedit callback in ajax.js

PHPBB3-12393