Bugfix: Show news for a given project

The problem is that registering the pootle_project URLs before the
pootle_notifications ones caused 'pootle-notifications-project-notices'
URL pattern to be never matched, and instead the 'pootle-project-overview'
URL pattern was the one that matched always.
Fix suggestion counts altering when accepting/rejecting
Move local TM creation to management command

This potentially leads to broken upgrade process in massive projects,
so it is better to have it clearly separated from it and avoid scaring
people.

Also having this in a separate management command allows further
refinements in the logic.
Local TM command: allow to wipe out previously existing local TM
Local TM command: Try to avoid DB locking

If we run this for a setup with hundreds of thousands of units we are
locking the DB for a really long time, and if the computer has not enough
resources it might even hang.
Stats: Don't display 'next goal' translation action in goal drill-down
Stats: Retrieve only the necessary children for calculating the stats
Stats: Display proper data in table items when drilling down

Note that caching for last updated and last activity was removed.
Stats: Use the right URLs for translate actions when drilling down
Changelog: Update all release notes to refer to 2.6.0 instead of 2.5.2