[tracker] (6 commits) ...Merge branch 'wip/carlosg/perf-improvements' into 'master'

[Sam Thursfield <sthursfield src gnome org>]

Summary of changes:

  6e37711... libtracker-data: Avoid revisiting already transacted parser (*)
  d9e6fb6... libtracker-sparql: Handle write errors with DBus cursors (*)
  127d7b6... libtracker-data: Release non-select statements (*)
  f5c7cc6... libtracker-data: Avoid unescaping unichar characters if unn (*)
  0a33f7c... libtracker-direct: Use the update thread for update_array o (*)
  18e8fbe... Merge branch 'wip/carlosg/perf-improvements' into 'master'

(*) This commit already existed in another branch; no separate mail sent