Flamenco: Added a hidden "Submit & Quit" button.

This button can be enabled in the add-on preferences and and then be
available on the Flamenco Render panel. Pressing the button will
silently close Blender after the job has been submitted to Flamenco (for
example to click, walk away, and free up memory for when the same
machine is part of the render farm).

blender_cloud/blender.py

@@ -267,6 +267,13 @@ class BlenderCloudPreferences(AddonPreferences):
         description='When enabled, Blender will open a webbrowser',
         default=True,
     )
+    flamenco_show_quit_after_submit_button = BoolProperty(
+        name='Show "Submit & Quit" button',
+        description='When enabled, next to the "Render on Flamenco" button there will be a button '
+                    '"Submit & Quit" that silently quits Blender after submitting the render job '
+                    'to Flamenco',
+        default=False,
+    )
 
     def draw(self, context):
         import textwrap
@@ -489,6 +496,7 @@ class BlenderCloudPreferences(AddonPreferences):
 
         flamenco_box.prop(self, 'flamenco_relative_only')
         flamenco_box.prop(self, 'flamenco_open_browser_after_submit')
+        flamenco_box.prop(self, 'flamenco_show_quit_after_submit_button')
 
 
 class PillarCredentialsUpdate(pillar.PillarOperatorMixin,