implement json_object_int_inc(json_object *, int64_t)

[dpintaric]

Hi,

Having json_object_set_int is great since I don't have to json_object_object_del() first but if I just want to inc the value I have to:

json_object_set_int(key_jobj, json_object_get_int(key_jobj) + 1);

Having json_object_inc_int() and json_object_inc_int64() would greatly optimize this when a interger object is beeing used as a counter.

[hawicz]

Sure, sounds good to me. A pull request would be welcome.