IN order to do screen review without lots of client processing and
many IPC calls, we need some more efficient API for relating
bounding boxes to ranges within an AccessibleText object.

At the moment we have bounds API for characters, but not ranges, so 
range information must be built up over many API calls.

Ideally we should have:

in Accessibility_Text.idl:

    void getRangeExtents (in long start_offset, in long end_offset,
                          out long x, out long y, 
                          out long length, out long width, 
                          in short coordType);

    void getRangeFromBounds (out long start_offset,
                             out long end_offset,
                             in long x, in long y, 
                             in long width, in long height,
                             in short coordType);
 



(with corresponding API in cspi).