(API Change) Refactor module handling

Changed API:
- char *obs_find_plugin_file(const char *sub_path);

  Changed to: char *obs_module_file(const char *file);

  Cahnge it so you no longer need to specify a sub-path such as:
  obs_find_plugin_file("module_name/file.ext")

  Instead, now automatically handle the module data path so all you need
  to do is:
  obs_module_file("file.ext")

- int obs_load_module(const char *name);

  Changed to: int obs_open_module(obs_module_t *module,
                                  const char *path,
                                  const char *data_path);
              bool obs_init_module(obs_module_t module);

  Change the module loading API so that if the front-end chooses, it can
  load modules directly from a specified path, and associate a data
  directory with it on the spot.

  The module will not be initialized immediately; obs_init_module must
  be called on the module pointer in order to fully initialize the
  module.  This is done so a module can be disabled by the front-end if
  the it so chooses.

New API:
- void obs_add_module_path(const char *bin, const char *data);

  These functions allow you to specify new module search paths to add,
  and allow you to search through them, or optionally just load all
  modules from them.  If the string %module% is included, it will
  replace it with the module's name when that string is used as a
  lookup.  Data paths are now directly added to the module's internal
  storage structure, and when obs_find_module_file is used, it will look
  up the pointer to the obs_module structure and get its data directory
  that way.

  Example:
  obs_add_module_path("/opt/obs/my-modules/%module%/bin",
                      "/opt/obs/my-modules/%module%/data");

  This would cause it to additionally look for the binary of a
  hypthetical module named "foo" at /opt/obs/my-modules/foo/bin/foo.so
  (or libfoo.so), and then look for the data in
  /opt/obs/my-modules/foo/data.

  This gives the front-end more flexibility for handling third-party
  plugin modules, or handling all plugin modules in a custom way.

- void obs_find_modules(obs_find_module_callback_t callback, void
                        *param);

  This searches the existing paths for modules and calls the callback
  function when any are found.  Useful for plugin management and custom
  handling of the paths by the front-end if desired.

- void obs_load_all_modules(void);

  Search through the paths and both loads and initializes all modules
  automatically without custom handling.

- void obs_enum_modules(obs_enum_module_callback_t callback,
                        void *param);

  Enumerates currently opened modules.

obs/window-basic-main.cpp

@@ -534,28 +534,7 @@ void OBSBasic::OBSInit()
 
 	InitOBSCallbacks();
 
-	/* TODO: this is a test, all modules will be searched for and loaded
-	 * automatically later */
-	obs_load_module("image-source");
-	// obs_load_module("test-input");
-	obs_load_module("obs-ffmpeg");
-	obs_load_module("obs-libfdk");
-	obs_load_module("obs-x264");
-	obs_load_module("obs-outputs");
-	obs_load_module("rtmp-services");
-#ifdef __APPLE__
-	obs_load_module("mac-avcapture");
-	obs_load_module("mac-capture");
-#elif _WIN32
-	obs_load_module("win-wasapi");
-	obs_load_module("win-capture");
-	obs_load_module("win-dshow");
-#else
-	obs_load_module("linux-xshm");
-	obs_load_module("linux-xcomposite");
-	obs_load_module("linux-pulseaudio");
-	obs_load_module("linux-v4l2");
-#endif
+	obs_load_all_modules();
 
 	if (!InitOutputs())
 		throw "Failed to initialize outputs";