bug(color TextItem not changable) solved through new attribute TextItem.text_color

the color in TextItem stayed white before

eg.
pg.TextItem(
            text='TEST', color='r', html=None, anchor=(
            0, 0), border=None, fill=pg.mkBrush(
            255, 255, 255, 80), angle=0)


For consistency, better to use pg.mkColor here (this allows, for example, `setColor('r')`).