Disable delete after shred was once started. (#69)

documented here: #65

Reviewed-on: #69
Co-authored-by: localhorst <localhorst@mosad.xyz>
Co-committed-by: localhorst <localhorst@mosad.xyz>

include/drive.h

@@ -34,6 +34,7 @@ public:
     } sShredSpeed;
 
     bool bWasShredded = false; // all shred iterations done
+    bool bWasShredStarted = false; // shred was atleast once started
     bool bWasChecked = false;  // all shred iterations and optional checking done
     bool bWasDeleted = false;
     bool bIsOffline = false;