sun-java6 should set himself as first choice if openjdk is installed

[Fabi]

Some sites (f.e. knuddels.de (a german kiddy-webchat)) and Applications (minecraft) only works with sun-java6(-plugin). atm its really hard to install this for new user. You have to enable partner sources. next you have to install sun-java6-plugin, and now you have to uninstall the openjdk or run a terminal with "sudo update-alternatives --set java /usr/lib/jvm/java-6-sun/jre/bin/java".
it would be much better if sun-java6 (AND the plugin) set himself as first choice after installation or conflicts with icedtea java-plugin) so that we have a really simple installations
with apturl -> apt:sun-java6-plugin?channel=$RELEASE-partner