(edit_buffer_calc_percent): new editor buffer API.

Modify way to calculate persentage: use byte offers instead of line one.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
mcedit: apply status message for search process.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
mcedit: apply status message for file load process.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>