lua move strip_extension and create_numbered_filename out of main binary

rb.strip_extension and rb.create_numbered_filename
have been moved to include_lua/files.lua
to use simply add require('files') to your script

Change-Id: I95af7b312c8614cb10da4b71b22714b3e282e08a

apps/plugins/lua/rocklib_aux.pl

@@ -109,8 +109,10 @@ my @forbidden_functions = ('^atoi$',
                            '^plugin_get_current_filename$',
                            '^plugin_release_audio_buffer$',
                            '^reload_directory$',
+                           '^settings_save$',
                            '^set_current_file$',
                            '^set_dirfilter$',
+                           '^show_logo$',
                            '^sleep$',
                            '^system_memory_guard$',
                            '^system_sound_play$',