Publishing transitions twice through draft

When a node is published via Scheduler and a moderation state is set, the published revision always has two transitions. One to draft, then one to published.

This patch fixes it by;

1. Make it easier to extend with implementations of scheduler_workbench_scheduler_api(); 1483c
2. Receive $node by reference for implementations of hook_scheduler_publish_api(); 3e843
3. Use Workbench Moderation's $node properties to trigger workbench_moderation_moderate() via hook_node_update() instead of calling it directly. This keeps the history cleaner because the moderation state is not reverted to draft when _scheduler_publish() calls node_save() but before _scheduler_workbench_publish() can set the new correct moderation state; 3e843

Item number 2 depends on a patch for Scheduler; #1660192: Expand options for integrating modules

This patch extends #1660208: Code style and line endings.