Merged from trunk 8492:8503

   Merged from trunk 8492:8503

   | 8493    | * Remove all references to the obsolete Package.digraph_node |
   | zmedico | attribute. * Reimplement Package comparison methods since    |
   |         | the previous way didn't seem to function properly for dict   |
   |         | keys. * Clean up depgraph._add_pkg() to use the Package      |
   |         | object attributes.                                           |

   | 8494    | Add DependencyArg instances as parents of packages in the    |
   | zmedico | digraph since these relationships should be useful during    |
   |         | backtracking.                                                |

   | 8495    | Remove the depgraph.pkg_node_map attribute and use other     |
   | zmedico | means to accomplish the same thing.                          |

   | 8496    | Make depgraph._add_pkg() match the package with all possible |
   | zmedico | args and add them to the digraph.                            |

   | 8497    | Make depgraph._complete_graph() properly specify SetArg      |
   | zmedico | instances as parents of each Dependency, similar to the want |
   |         | that select_files() does.                                    |

   | 8498    | Make the slot collision display show all collisions instead  |
   | zmedico | of just the first one.                                       |

   | 8499    | Make 'full' the default mode, since 'scan' can be annoying   |
   | zmedico | since it ommits relevant info.                               |

   | 8500    | In the slot collision display, show a maximum of 3 parents   |
   | zmedico | for each package in order to avoid flooding the display.     |

   | 8501    | * Replace references to deprecated ${IMAGE} with equivalent  |
   | zmedico | ${D}. * Remove redundant trailing slashes and fix quoting.   |

   | 8502    | Make dir_get_metadata() return early if the current user     |
   | zmedico | does not have write access to /var/cache/edb. Thanks to      |
   |         | Cardoe for reporting.                                        |

   | 8503    | Fix quoting for `source ${EBUILD}`.                          |
   | zmedico |                                                              |

svn path=/main/branches/prefix/; revision=8506