Ticket #3152: fix unconventional behavior of "Display bits" dialog.

Use codepage name as button name:

Input / display codepage: [ UTF-8 ]

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '3152_display_bits'

* 3152_display_bits:
  Ticket #3152: fix unconventional behavior of "Display bits" dialog.