Updated proto file

Objects & global settings are now sent in one message.
Also added support for extruder settings

CURA-1681

plugins/CuraEngineBackend/Cura.proto

@@ -11,6 +11,8 @@ message ObjectList
 message Slice
 {
     repeated ObjectList object_lists = 1;
+    SettingList global_settings = 2;
+    repeated SettingsList extruder_settings = 3;
 }
 
 message Object