Comment 4 for bug 439431

Will be resolved for 10.04.

Implemetion details:
* kfi should have it's desktop file named firefox.desktop
* the firefox package (also shipping firefox.desktop) should be marked Replaces kfi
* when firefox gets installed the kfi desktop file will be overwritten, when uninstalled the kfi desktop file should re-appear making it possible to install firefox again via the installer

Additional considerations:
* kdesudo probably finds desktop file by command name, so we need to enhance kdesudo to accept a desktop file as argument (such as gksu does already)
* when changing the desktop file name, the translation domain also needs to be renamed
* changes must not make the system uninstall firefox upon upgrade