Add an example plugin to demonstrate Lua global variables

Note: this only works when loading the script action.
Window > Scripting doesn't run the factory method for upindex variables

scripts/_remember_file.lua

@@ -0,0 +1,37 @@
+ardour {
+	["type"] = "EditorAction",
+	name = "File Name Test",
+	author = "Ardour Lua Taskforce",
+	description = [[Example Plugin to show to to select a file and remember the most recently used file.]]
+}
+
+function factory ()
+	local file_name_testscript_last_filename -- this acts as "global" variable, use a unique name
+	return function ()
+		print (file_name_testscript_last_filename) -- debug
+
+		--set filename to most recently used, fall back to use a default
+		local fn = file_name_testscript_last_filename or ARDOUR.LuaAPI.build_filename (Session:path (), Session:name () .. ".ardour")
+
+		-- prepare a dialog
+		local dialog_options = {
+			{ type = "file", key = "file", title = "Select a File",  path = fn }
+		}
+
+		-- show dialog
+		local od = LuaDialog.Dialog ("title", dialog_options)
+		local rv = od:run()
+
+		if rv then
+			-- remember most recently selected file
+			file_name_testscript_last_filename = rv['file']
+			LuaDialog.Message ("title", "set path to " .. file_name_testscript_last_filename, LuaDialog.MessageType.Info, LuaDialog.ButtonType.Close):run()
+		else
+			-- unset most recently used filename on dialog "cancel"
+			file_name_testscript_last_filename = nil
+		end
+
+		od = nil
+		collectgarbage ()
+	end
+end