Ticket #3123: clarify file operation prompt.

In the delete confirmation dialog, the question mark is on its own line.
This is gramatically incorrect in English.

(panel_operate_generate_prompt): totally rewrite.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Refresh po/*.po files.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '3123_file_operation_prompt'

* 3123_file_operation_prompt:
  Refresh po/*.po files.
  Ticket #3123: clarify file operation prompt.