Add function to get current core version

The version macro that modules use to compile versus the actual core
version that may be in use may be different, so this is a way to compare
them to check for compatibility issues later on.

libobs/obs.c

@@ -596,6 +596,11 @@ bool obs_initialized(void)
 	return obs != NULL;
 }
 
+uint32_t obs_get_version(void)
+{
+	return LIBOBS_API_VER;
+}
+
 void obs_set_locale(const char *locale)
 {
 	if (!obs)

libobs/obs.h

@@ -211,6 +211,9 @@ EXPORT void obs_shutdown(void);
 /** @return true if the main OBS context has been initialized */
 EXPORT bool obs_initialized(void);
 
+/** @return The current core version */
+EXPORT uint32_t obs_get_version(void);
+
 /**
  * Sets a new locale to use for modules.  This will call obs_module_set_locale
  * for each module with the new locale.