Log of changes to DragASprite

Version 0.02

 *  Fix bug whereby bounding box for pointer ended up incorrect
 *  Fix bug whereby bounding box for drop shadow ended up incorrect
 *  Fix bug whereby box returned at end of drag was different to box supplied at start of drag

Version 0.06

 * (DDV) added dithered dragging
 * Added some support for Medusa 16/32bpp modes

Version 0.12

* Fixed bug which meant translation table used for ROM sprites was corrupt - since they have
  traditionally been 16-colour sprites, it defaulted to the Wimp palette, and nobody noticed
* Added checking of Wimp_ReadSysInfo 16 to determine the ROM/RAM sprite pool relative priority

Version 0.13

* Added flag bit (bit 9) to DragASprite_Start SWI. If set, icon is placed at pointer position
  and bits 0-3 are ignored.