en to en_AU translation catalogue (3 entries)

[ctx: Label of a button that allows selecting a font color.]
en: Font Color
en_AU: Font Colour

[ctx: Label of a button that allows selecting a font background color.]
en: Font Background Color
en_AU: Font Background Colour

[ctx: Title of a color picker section containing the colors currently used in the document.]
en: Document colors
en_AU: Document colours
