Add simple image debug test

source/main.cpp

@@ -179,6 +179,14 @@ int main() {
 
     UBIT.display.scroll("BLOCKS!");
 
+    // XXX: simple debug test to check my FLASH images were stored correctly
+    while (true) {
+        // display new random blocks each second
+        Block block;
+        UBIT.display.print(block.image(), 1, 1);
+        UBIT.sleep(1000); // 1000ms or 1s sleep
+    }
+
     // TODO: potentially remove this call, if clarified that it is not required.
     // If main exits, there may still be other fibers running or registered event handlers etc.
     // Simply release this fiber, which will mean we enter the scheduler. Worse case, we then