Merged from trunk 8043:8051

   Merged from trunk 8043:8051

   | 8044    | implement new set to group all consumers of preserved        |
   | genone  | libraries                                                    |

   | 8045    | Make depgraph.select_dep() reject installed packages in the  |
   | zmedico | same cases that it used to so that a warning message is      |
   |         | properly generated in depgraph.xcreate() when a package is   |
   |         | unavailable but installed.                                   |

   | 8046    | Add a set to group all consumers of missing libraries as a   |
   | genone  | simple revdep-rebuild replacement                            |

   | 8047    | Update todo list                                             |
   | genone  |                                                              |

   | 8048    | Do not use aux_get to parse the NEEDED file as we need to    |
   | genone  | distinguish spaces and newlines                              |

   | 8049    | typo fix                                                     |
   | genone  |                                                              |

   | 8050    | In depgraph.select_dep(), check for existing nodes in        |
   | zmedico | installed packages when necessary.                           |

   | 8051    | Strip the leading path separator from USER_CONFIG_PATH so    |
   | zmedico | that os.path.join works correctly.                           |

svn path=/main/branches/prefix/; revision=8076