Dynamic engine options in UI for blender / ffmpeg (#66)

* Make sure progress UI updates occur on main thread

* Cleanup unnecessary code in FFMPEG

* Cleanup extension matching

* Make sure supported_extensions is now called as a method everywhere

* Fix add_job crashing

* Update the renderer to reflect the current file type

* Sort engine versions from newest to oldest

* Consolidate Project Group and Server Group

* Split UI options into its own file for easier updating

* Add ffmpeg ui stem

src/engines/core/base_engine.py

@@ -47,7 +47,10 @@ class BaseRenderEngine(object):
     def worker_class():  # override when subclassing to link worker class
         raise NotImplementedError("Worker class not implemented")
 
-    def get_help(self):
+    def ui_options(self):  # override to return options for ui
+        return {}
+
+    def get_help(self):  # override if renderer uses different help flag
         path = self.renderer_path()
         if not path:
             raise FileNotFoundError("renderer path not found")
@@ -56,7 +59,7 @@ class BaseRenderEngine(object):
         return help_doc
 
     def get_project_info(self, project_path, timeout=10):
-        raise NotImplementedError(f"get_project_info not implemented for {cls.__name__}")
+        raise NotImplementedError(f"get_project_info not implemented for {self.__name__}")
 
     @classmethod
     def get_output_formats(cls):