blender: Fix bug where c-ray was never deleted

Turns out, I was passing self into the callback args, which presumably
then held a reference to it, which meant that the Blender python runtime
never calls __del__() on it. I wasn't even using self for anything, I
was just grabbing the current sample count from it.
Fix is to just pass in the sample count directly, instead of passing in
self.

bindings/blender_init.py

@@ -170,9 +170,9 @@ def draw_direct(bitmap):
 		draw_texture_2d(texture, (0, 0), texture.width, texture.height)
 
 def status_update_interactive(cb_info, args):
-	tag_redraw, update_stats, self = args
+	tag_redraw, update_stats, total_samples = args;
 	tag_redraw()
-	if cb_info.finished_passes == self.cr_renderer.prefs.samples:
+	if cb_info.finished_passes == total_samples:
 		update_stats("Rendering done", "")
 	else:
 		update_stats("Sample {}".format(cb_info.finished_passes), "")
@@ -193,8 +193,6 @@ def __init__(self):
 		c_ray.log_level_set(c_ray.log_level.Debug)
 
 	def __del__(self):
-		# FIXME: This never gets called when leaving rendered viewport shading mode
-		# which ends up leaving zombie instances of c-ray running in the background
 		if self.cr_renderer:
 			if self.cr_renderer.interactive:
 				self.cr_renderer.stop()
@@ -481,7 +479,7 @@ def view_update(self, context, depsgraph):
 			sync_end = time.time()
 			print("Sync took {}s".format(sync_end - sync_start))
 			print("Kicking off background renderer")
-			self.cr_renderer.callbacks.on_interactive_pass_finished = (status_update_interactive, (self.tag_redraw, self.update_stats, self))
+			self.cr_renderer.callbacks.on_interactive_pass_finished = (status_update_interactive, (self.tag_redraw, self.update_stats, self.cr_renderer.prefs.samples))
 			self.cr_renderer.start_interactive()
 
 	def display_bitmap(self, bm):