Merged from trunk 11111:11124

   Merged from trunk 11111:11124

   | 11112   | Since it's not very interesting, disable the "merges" part   |
   | zmedico | of status display.                                           |

   | 11113   | Also, don't count "merges" as changes in the status display. |
   | zmedico |                                                              |

   | 11114   | Initialize JobStatusDisplay.merges since it's not            |
   | zmedico | initialized with the bound properties anymore.               |

   | 11115   | Also, reset "merges" in JobStatusDisplay.reset().            |
   | zmedico |                                                              |

   | 11116   | When dblink is looping over files for merge/unmerge,         |
   | zmedico | temporarily yield to the scheduler each time a fixed number  |
   |         | of files are processed (currently 20). This gives the        |
   |         | scheduler an opportunity to service pending poll events.     |
   |         | This is implemented with a new                               |
   |         | PollScheduler._schedule_yield() method which calls poll()    |
   |         | exactly once, without blocking, and any services any         |
   |         | resulting poll events.                                       |

   | 11117   | Redirect dblink elog messages from stdout to the log file    |
   | zmedico | when in background mode. This is implemented by adding a new |
   |         | "out" parameter to the portage.elog.e* functions, which can  |
   |         | be used to send output to an arbitary file instead of        |
   |         | stdout.                                                      |

   | 11118   | If an problem is detected in dblink._security_check(), log   |
   | zmedico | it via elog so that it's properly displayed in the           |
   |         | foreground even when in background mode.                     |

   | 11119   | Use dblink._eerror() to eliminate duplicate code.            |
   | zmedico |                                                              |

   | 11120   | In dblink._dblink_display_merge(), when in background mode   |
   | zmedico | and no log is available, suppress output when level <        |
   |         | logging.WARNING. This hides ">>> Regenerating                |
   |         | /etc/ld.so.cache..." messages that appear after postrm when  |
   |         | PORT_LOGDIR is unset (the log file if it exists is removed   |
   |         | after postrm so there's no place to log the message).        |

   | 11121   | Change package status messages to give more accurate         |
   | zmedico | information about what is happening at a given time: *       |
   |         | Change "Emerging" messages to "Building" for ebuilds and     |
   |         | "Extracting" for binary packages. * Change "Merging"         |
   |         | messages to "Installing" and "Uninstalling".                 |

   | 11122   | Add background output redirection and async ebuild phase     |
   | zmedico | support for PackageUninstall (automatic uninstalls that      |
   |         | solve blockers).                                             |

   | 11123   | Suppress counter initialization warning messages in          |
   | zmedico | vardbapi.get_counter_tick_core() in cases when the vdb is    |
   |         | empty. This avoids pointless error messages when merging     |
   |         | packages into a new root, like when building stage 1.        |

   | 11124   | Fix typo.                                                    |
   | zmedico |                                                              |

svn path=/main/branches/prefix/; revision=11125