updated example scripts to use darktable translation facilities

examples/hello_world.lua

@@ -29,15 +29,23 @@ USAGE
 local dt = require "darktable"
 local du = require "lib/dtutils"
 
+-- translation facilities
+
 du.check_min_api_version("2.0.0", "hello_world") 
 
+local gettext = dt.gettext.gettext
+
+local function _(msg)
+  return gettext(msg)
+end
+
 -- script_manager integration to allow a script to be removed
 -- without restarting darktable
 local function destroy()
     -- nothing to destroy
 end
 
-dt.print("hello, world")
+dt.print(_("hello, world"))
 
 -- set the destroy routine so that script_manager can call it when
 -- it's time to destroy the script and then return the data to