[gedit-list] activate text-adjust button in headbar

["Htëchnö mkö" <mkotechno gmail com>]

hello, I'm not sure this mail is right here

will be nice a headbar button to enable/disable text-adjust, I think it's very cumbersome to have to access the preferences to change something so common to switch between programing and reading text mode

thanks and excuse me for my poor english