Ticket #2245: mcedit: entire file wordcompletion failed

...if word to be comleted is begun from begin of file.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '2245_mcedit_autocompletion_fix'

* 2245_mcedit_autocompletion_fix:
  Ticket #2245: mcedit: entire file wordcompletion failed