Created attachment 45281 [details] [review]
the proposed patch for public add group/key functions

In this patch, I've rename the add_key/add_group functions as
real_add_key/real_add_group, and added two public functions:

void g_key_file_add_group (GKeyFile	*key_file,
			   const gchar	*group_name,
			   GError      **err);
void g_key_file_add_key   (GKeyFile	*key_file,
			   const gchar	*group_name,
			   const gchar	*key_name,
			   GError      **err);

I've also added two new erro constants, one for duplicate group and one for
duplicate key.

We had those functions in an earlier draft of the keyfile api, but dropped them,
since it seems better to just create groups as needed in the set_key functions.