(API Change) Split obs_source_gettype

Changed:
- obs_source_gettype
To:
- enum obs_source_type obs_source_get_type(obs_source_t source);
- const char *obs_source_get_id(obs_source_t source);

This function was inconsistent for a number of reasons.  First, it
returns both the ID and the type of source (input/transition/filter),
which is inconsistent with the name of "get type".  Secondly, the
'squishy' naming convention which has just turned out to be bad
practice and causes inconsistencies.  So it's now replaced with two
functions that just return the type and the ID.

libobs/obs.h

@@ -646,9 +646,11 @@ EXPORT const char *obs_source_getname(obs_source_t source);
 /** Sets the name of a source */
 EXPORT void obs_source_setname(obs_source_t source, const char *name);
 
-/** Gets the source type and identifier */
-EXPORT void obs_source_gettype(obs_source_t source, enum obs_source_type *type,
-		const char **id);
+/** Gets the source type */
+EXPORT enum obs_source_type obs_source_get_type(obs_source_t source);
+
+/** Gets the source identifier */
+EXPORT const char *obs_source_get_id(obs_source_t source);
 
 /** Returns the signal handler for a source */
 EXPORT signal_handler_t obs_source_signalhandler(obs_source_t source);