UI: Add SelectScene hotkey

UI supplied per scene hotkey to allow switching between scenes; this
has to be done in the UI since it's up to the application to define
what exactly "changing/selecting a scene" means (changing the output
of channel 0 may not be enough for other applications)

obs/data/locale/en-US.ini

@@ -361,6 +361,9 @@ Basic.AdvAudio.AudioTracks="Tracks"
 Basic.Settings.Hotkeys="Hotkeys"
 Basic.Settings.Hotkeys.Pair="Key combinations shared with '%1' act as toggles"
 
+# basic mode hotkeys
+Basic.Hotkeys.SelectScene="Switch to scene"
+
 # hotkeys that may lack translation on certain operating systems
 Hotkeys.Insert="Insert"
 Hotkeys.Delete="Delete"

obs/window-basic-main.cpp

@@ -918,6 +918,18 @@ void OBSBasic::AddScene(OBSSource source)
 	item->setData(Qt::UserRole, QVariant::fromValue(OBSScene(scene)));
 	ui->scenes->addItem(item);
 
+	obs_hotkey_register_source(source, "OBSBasic.SelectScene",
+			Str("Basic.Hotkeys.SelectScene"),
+			[](void *data,
+				obs_hotkey_id, obs_hotkey_t*, bool pressed)
+	{
+		auto potential_source = static_cast<obs_source_t*>(data);
+		auto source = obs_source_get_ref(potential_source);
+		if (source && pressed)
+			obs_set_output_source(0, source);
+		obs_source_release(source);
+	}, static_cast<obs_source_t*>(source));
+
 	signal_handler_t *handler = obs_source_get_signal_handler(source);
 	signal_handler_connect(handler, "item_add",
 			OBSBasic::SceneItemAdded, this);