[tracker] (15 commits) Created branch threaded-extractor

[Martyn James Russell <mr src gnome org>]

The branch 'threaded-extractor' was created.

Summary of new commits:

  cf22cfe... tracker-miner-fs: Revert commit 3dd75bacc30
  8daecc8... libtracker-extract: Add tracker-extract-client API
  764f5d8... tracker-miner-fs: Move "retry on extraction failed" code to
  9140543... tracker-miner-fs: Implement failsafe metadata extraction
  5dfab13... tracker-extract: Implement watchdog for stale tasks.
  fa3af01... libtracker-extract: Document tracker-client API
  89e3f45... libtracker-extract: Do not use G_CONST_RETURN
  ad2a833... tracker-miner-fs: Don't remove item from queue until it's b
  bae1516... tracker-miner-fs: Avoid multiple calls to extractor_process
  9800e59... tracker-extract: Implement thread awareness for modules
  a1fd916... tracker-extract: Mark text extractor as thread aware
  d1c5954... tracker-extract: Rework stats reporting and task cancellati
  f558409... libtracker-extract: Add API to iterate through the modules 
  e14ca1e... tracker-extract: Use API to iterate through extract modules
  713c702... libtracker-miner: Use tracker_processing_task_unref() inste