Issue #2304137 by lmeurs: Fixed "Notice: Use of undefined constant L10N_UPDATE_DEFAULT_TRANSLATION_PATH".

Issue #2237959 by René-Marc Simard: Fixed Collapsible project titles not working if only one language defined.

Added 'translations' steam wrapper.

Issue #2201931 by Sutharsan: l10n_update and i18n_string together enabled doesn't set l10n_status in db.
Only update l10n_status if translation has changed.

Improved (error) messages.
Removed admin options for one-time change of update mode.

Issue #1923522 by Sutharsan | martink: 'Use local files only' seems to be ignored when modules are enabled.

Fixed #1671570 by Sutharsan: Added check for Update module to 'Fetch available module versions if Update module doesn't.'

Fixed #2068683 by catch: hook_requirements() causes a refresh even when update frequency is set to 'check manually'

Issue #1883154 by Sutharsan: Translation version should not be more recent than core or module version.

Issue #1837704 by lambic, Sutharsan: Stop spamming the watchdog log with 'Automatically checked 0 translations, updated 0.'

Issue #1554570 by ralf57, igor.ro, Sutharsan: drush l10n-update command doesn't take the mode option into account