fix: don't register adhesion_extruder_nr as used if adhesion_type == none (CURA-759)

Also the old line obtained brim_line_count from the global stack, while it is settable_per_extruder!
Also we now assume selecting a brim means you want to print it.
I don't think having a brim line count of zero meant that you wouldnt get a brim; the minimal brim length also plays a role...

cura/Settings/ExtruderManager.py

@@ -336,8 +336,8 @@ class ExtruderManager(QObject):
             if support_interface_enabled:
                 used_extruder_stack_ids.add(self.extruderIds[str(global_stack.getProperty("support_interface_extruder_nr", "value"))])
 
-        #The platform adhesion extruder. Not used if using brim and brim width is 0.
-        if global_stack.getProperty("adhesion_type", "value") != "brim" or global_stack.getProperty("brim_line_count", "value") > 0:
+        #The platform adhesion extruder. Not used if using none.
+        if global_stack.getProperty("adhesion_type", "value") != "none":
             used_extruder_stack_ids.add(self.extruderIds[str(global_stack.getProperty("adhesion_extruder_nr", "value"))])
 
         return [container_registry.findContainerStacks(id = stack_id)[0] for stack_id in used_extruder_stack_ids]