Revision 2774

INCOMPATIBLE CHANGE with Thuban 1.1 (development series) and 1.2.0:
Changing the raster layer attributes towards always 
using an alpha channel. As we require wx2.6 there is no real use-case 
for bitmap and this fixes a problem on the windows platform.

* NEWS: adding note about the major change using alpha always.

* Thuban/UI/renderer.py: Removed diversion for wx <2.5.3 as 
we require >= 2.6 now. Bumping copyright, adding author Bernhard.

* Thuban/UI/rasterlayerproperties.py: Removed diversion for
wx <2.5.3 as we require >= 2.6 now, so we always can do alpha channel. 
Added author Bernhard Reiter and copyright year 2007. 
Removed two old code lines which were commented out.
Commented out the code for the mask type selection.

* Thuban/Model/layer.py: Made masktype = MASK_ALPHA default for new
raster images. Bumping copyright.

* test/test_layer.py: made test_raster_layer() expect MASK_ALPHA.
Bumping copyright.

* Thuban/Model/load.py: if there is no masktype set, use alpha.
This means the behaviour changes for files saved with Thuban-1.1,
but this has been a development version. As bitmap does not work
on some platforms (windows currently) it will even fix a problem 
there. Bumping copyright

* test/test_load.py: Removed masktype from example file. Bumping
copyright.

* Thuban/Model/save.py: Do not save raster attribute "masktype" 
anymore. Bumping copyright.

* test/test_save.py: Not expecting "masktype" to be saved anymore.
Bumping copyright.