Lab: Implemented a ChangedSinceLastSave monitor.
Lab: VM is now aware of its save path.
Lab: Save-before-closing confirmation. (...)

- Applied on Window.Closing and on New file.
- File name and changed status is displayed in window title.
Lab: Autosave every five seconds! (...)

- Not applicable if saving file was explicitly refused when closing window.
- Attempts to load autosave on startup.
IDiscoveredInfo.IsValid(): Service references are now sanity-checked. (...)

- Lab will now check for discrepancies related to service references.
- Small size fixes for service and plugin creation windows.
Engine.Tests: XML deserialization. (...)

- Fixed MWVM tests.
Lighter background for disabled/enabled items.
Merge branch 'feature/ui-advanced-save' into develop