Debian: update patch to compensate for last commit

At the same time I'm making more Debian-specific changes, such as
 - not checking for Gentoo (this is obviously never going to be true :P)
 - not mentioning IzPack replacing variables (also not applicable)
 - inform about dpkg-reconfigure i2p in the event someone tries to remove or
   install an initscript with "i2prouter install|remove|uninstall"
 - remove the manual wrapper instructions