Rename renderers to engines (#123)

* Bulk rename
* Fix build issues

src/render_queue.py

@@ -46,7 +46,7 @@ class RenderQueue:
         try:
             not_started = cls.jobs_with_status(RenderStatus.NOT_STARTED, priority_sorted=True)
             for job in not_started:
-                if cls.is_available_for_job(job.renderer, job.priority):
+                if cls.is_available_for_job(job.engine_name, job.priority):
                     cls.start_job(job)
 
             scheduled = cls.jobs_with_status(RenderStatus.SCHEDULED, priority_sorted=True)
@@ -145,7 +145,7 @@ class RenderQueue:
     @classmethod
     def renderer_instances(cls):
         from collections import Counter
-        all_instances = [x.renderer for x in cls.running_jobs()]
+        all_instances = [x.engine_name for x in cls.running_jobs()]
         return Counter(all_instances)
 
     @classmethod