In the dialog layout code, fixed the button padding.

There was no check if the "text_and_image_height"
variable was equal to zero. If so, the buttons were
placed -6 units too high.
Modified the changelog and added myself to the credits.
Merge remote-tracking branch 'LovCAPONE/TopButtonStatsCutOff'

Conflicts:
	changelog
Merge branch 'master' of https://github.com/wesnoth/wesnoth