Magick++ DrawableRoundRectangle attribute names are misleading

[Brian Nixon]

The Magick++ class DrawableRoundRectangle has attributes named centerX, centerY, width and hight whose values are passed to the MagickWand function DrawRoundRectangle() which interprets them as x1, y1, x2 and y2.

It might be clearer if the attributes had names that reflected their usage and were consistent with the class DrawableRectangle (i.e., upperLeftX, upperLeftY, lowerRightX and lowerRightY).