util: add int_or_none function
util: add int_or_none function

This is a version of int() that tolerates None argument:
return None if argument is None, otherwise, convert to int.

Signed-off-by: Ilija Hadzic <47a09d4a4430975766160361f65fc72633be50b6@gmail.com>

ihadzic/jim,ihadzic/jim,ihadzic/jim