Add Miscellaneous#onMainThread method

base/src/main/java/de/staropensource/sosengine/base/utility/Miscellaneous.java

@@ -163,4 +163,14 @@ public final class Miscellaneous {
                 return separator;
         return null;
     }
+
+    /**
+     * Ensures that the code is running on the main thread.
+     *
+     * @return {@code true} if running on the main thread, {@code false} otherwise
+     * @since v1-alpha2
+     */
+    public static boolean onMainThread() {
+        return Thread.currentThread().threadId() == 1;
+    }
 }