Fixed cb_known_board_copy() which was simply incomplete.

It needs to call config_keyfile_copy_with_templates() but couldn't since it didn't have the proper input.

Added fancy C99 code to build a specialized copy of the 'board_settings' SettingTemplate array that has the proper group in it.

This makes the rather peculiar boards settings look like regular global settings, and allows config_keyfile_copy_with_templates() to work.