isCircleOverlap( x1, y1, diameter1, x2, y2, diameter2, isCentred = false )
Returns true if the two circles given overlap, and otherwise return false. x1, y1 and diameter1 describe the location and size of the first circle, whilst x2, y2 and diameter2 refer to the second circle.
isCentred states if the x and y locations refer to the middle of the circle (when it is true), or the top left corner (when it is false). The default is false.