zsh completion: add all known aliases

They will complete even if the alias isn't present in PATH though
Also explicit the need to remove completion cache

extras/analyser/zsh.cpp

@@ -72,7 +72,7 @@ int main( int i_argc, const char **ppsz_argv )
         return 1;
     }
 
-    printf("#compdef vlc\n\n"
+    printf("#compdef vlc cvlc rvlc svlc mvlc qvlc nvlc\n\n"
 
            "#This file is autogenerated by zsh.cpp\n"
            "typeset -A opt_args\n"

extras/analyser/zsh_completion.sh

@@ -114,5 +114,6 @@ read i
 echo "Installing completion ..."
 sudo sh -c "chown 0:0 _vlc && chmod 0644 _vlc && mv _vlc $ZSH_FPATH" || exit 1
 
-echo "zsh completion for VLC successfully installed :)
-Restart running zsh instances, or run \"compinit\" to start using it."
+echo "zsh completion for VLC successfully installed :)"
+echo "Restart running zsh instances after removing ~/.zcompdump, or"
+echo "run \"compinit\" to start using it."