Fix symlink issue. See https://drupal.org/node/1372442#comment-6099598
#924: Return an array from drush_invoke_process when executed in interactive mode.
Added path-aliases option %env-vars for adding environmental variables to generated Drush commands.
Moved %env-vars to the top-level of site record as #env-vars.
Set 'drush' as the default backend in update_status engine.
Parts of Drupal still require a global user object.

- Fixes issue #957.
- Increases bootstrap level of the `user-cancel` command
Adjust update_status drush backend to match output of update.module.
Adding links to core issue.
Fix #936. Global option for skipping cache-clear during updb
Merge pull request #958 from drush-ops/user-cancel

Parts of Drupal still require a global user object.
Merge pull request #955 from mortenson/master

Added %env-vars for adding environmental variables to Drush commands
Merge pull request #952 from greg-1-anderson/interactive-fix

#924: Return an array from drush_invoke_process
Fix #947: pick the correct site for cache-rebuild.
Merge pull request #566 from in2pire/master

drush dl (--gitsubmodule) downloads extra pieces into /modules (and points there with .gitmodules) when symlinked parent dir
Back out 24addcdd; it is important that we set DRUSH_BACKEND in concert with the call to ob_start.
Merge pull request #966 from greg-1-anderson/drush_backend

Fix backend output to console
Supports injecting info file metatdata into YAML files.

- Fixes issue #943
Core check should be future-proof, not 8.x-specific.
Use heredoc templates for info metadata.
Metadata rewriting matches drupal.org.

- Uses double quotes for .info files
- Uses single quotes for .info.yml files
- Adds a yaml metadata rewrite test