Rework .stignore functionality (fixes #561) (...)

- Only one .stignore is supported, at the repo root
 - Negative patterns (!) are supported
 - Ignore patterns affect sent and received indexes, not only scanning

gui/app.js

@@ -971,9 +971,9 @@ function debounce(func, wait) {
         } else {
             timeout = null;
             if (again) {
+                again = false;
                 result = func.apply(context, args);
                 context = args = null;
-                again = false;
             }
         }
     };