[tracker] (23 commits) Created branch async-queries-wip

[Jürg Billeter <juergbi src gnome org>]

The branch 'async-queries-wip' was created.

Summary of new commits:

  e21c43c... libtracker-data: Add execute_async method to SparqlQuery cl
  5120be6... tracker-store: Use async queries
  5376bb8... libtracker-db: Fix TrackerDBResultSet type check defines.
  7b7be15... libtracker-db: Add TrackerDBInterfacePool.
  f7cdc37... TrackerDBInterfacePool: Add job prioritization.
  1501d41... TrackerDBInterfacePool: Fix memory leak.
  d5efb16... tracker-db-manager: Add tracker_db_manager_get_interface_po
  14adb88... libtracker-data: Adapt to new libtracker-db async API
  401063e... libtracker-db: Drop extra row in async query results
  f36e0a8... libtracker-db: Support empty result sets in async queries
  3351661... libtracker-db: Fix NULL interface_pool unref
  3acc1da... libtracker-data: Enable shared cache mode and require SQLit
  7040204... libtracker-db: Keep unused threads around for some time
  4a25dc6... libtracker-db: Use multi-thread instead of serialized mode 
  b87aba2... Added unit test for TrackerDBInterfacePool.
  a01bfa0... WIP
  ed6c51c... switch back
  99fb158... Fix fts (__thread yet needs to be replaced by g_private)
  fbbc8e5... disable shared cache mode
  db18f6a... WIP
  42bf98f... WIP
  f8bd8d5... threading changes
  e46883f... libtracker-db: Revert cache changes