need main() for go plugins

Signed-off-by: Jeff Carr <jcarr@wit.com>

main.go

@@ -49,6 +49,7 @@ func guiMain() {
 			log.Println("Stack trace:")
 			debug.PrintStack()
 			me.myTree.DoToolkitPanic()
+			return
 		}
 	}()
 	ui.Main(func() {
@@ -80,3 +81,6 @@ func init() {
 	// actually, this probably breaks the macos build
 	go guiMain()
 }
+
+func main() {
+}

updateui.go

@@ -101,9 +101,3 @@ func demoUI() {
 	// this is messed up.
 	// mainWindow.Show()
 }
-
-/*
-func main() {
-	ui.Main(setupUI)
-}
-*/