src/utils.c: Break out format specifier parsing
src/utils.c: Break out format specifier parsing

Move the format specifier parser to a separate function. This is done in
preparation for supporting long format specifiers.

Signed-off-by: Lukas Fleischer <af90e31281d8305af43dc616c5aaca3c7165f8a7@cryptocrack.de>

lfos/calcurse,lfos/calcurse,lfos/calcurse