As of version: 1.2.0, RgoogleMaps will only offer support for png files, no more jpeg.
The maintenance of the jpg ReadImages library has become too tedious, so I
removed all dependencies.

version 1.2.0.2:
- added function ColorMap to plot levels of a variable in a colour-coded map; This function takes sp objects directly!
- added function SpatialToPBS to convert spatial objects as defined in package sp to simpler PBSmapping type dataframes
- added spatial datasets pennLC, columbus and NYleukemia