obs-data: Internally store as int or double

If integers are used, then store as integers.  If doubles are used, then
store as doubles.  This way precision issues are prevented.

libobs/obs-data.h

@@ -46,6 +46,12 @@ enum obs_data_type {
 	OBS_DATA_ARRAY
 };
 
+enum obs_data_number_type {
+	OBS_DATA_NUM_INVALID,
+	OBS_DATA_NUM_INT,
+	OBS_DATA_NUM_DOUBLE
+};
+
 /* ------------------------------------------------------------------------- */
 /* Main usage functions */
 
@@ -122,6 +128,7 @@ EXPORT void obs_data_item_remove(obs_data_item_t *item);
 
 /* Gets Item type */
 EXPORT enum obs_data_type obs_data_item_gettype(obs_data_item_t item);
+EXPORT enum obs_data_number_type obs_data_item_numtype(obs_data_item_t item);
 
 /* Item set functions */
 EXPORT void obs_data_item_setstring(obs_data_item_t *item, const char *val);