Allow -i and -u as aliases for installed and upgradable in list

This makes things much easier to use

apt-private/private-cmndline.cc

@@ -248,9 +248,9 @@ static bool addArgumentsAPT(std::vector<CommandLine::Args> &Args, char const * c
 {
    if (CmdMatches("list"))
    {
-      addArg(0,"installed","APT::Cmd::Installed",0);
+      addArg('i',"installed","APT::Cmd::Installed",0);
       addArg(0,"upgradeable","APT::Cmd::Upgradable",0);
-      addArg(0,"upgradable","APT::Cmd::Upgradable",0);
+      addArg('u',"upgradable","APT::Cmd::Upgradable",0);
       addArg(0,"manual-installed","APT::Cmd::Manual-Installed",0);
       addArg('v', "verbose", "APT::Cmd::List-Include-Summary", 0);
       addArg('a', "all-versions", "APT::Cmd::All-Versions", 0);