#50 Change image extension based on format

[Tim Sutton]

I have updated the openModeller Desktop to allow user selection of output image format. This works fine with local plugin but for soap adapter the correct format extension should be used when writing and returning the file. It will probably work from the client side as the file is appropriately renamed when it is retrieved but for completeness the correct name should be written on the server side too.

[regiov]

The server uses the corresponding extension for each possible raster format. This was fixed a few years ago.