src/custom.c: Use status_ask_simplechoice()
src/custom.c: Use status_ask_simplechoice()

This eases up i18n somewhat, since the various date format available
are used on other places as well, and thus need to be translated only
once.

Note that this commit incidentally fixes a small bug introduced by
38912b36: the user was able to set the date input format to a number
between 1 and 5, while there are only 4 such formats available.

Signed-off-by: Baptiste Jonglez <b0aa5ae32cbebcf8fc6e0ec388d02a4f84ec737b@jonglez.org>
Signed-off-by: Lukas Fleischer <af90e31281d8305af43dc616c5aaca3c7165f8a7@cryptocrack.de>

lfos/calcurse,lfos/calcurse,lfos/calcurse