remove hour, add advanced section

libs/core/basic.cpp

@@ -75,6 +75,7 @@ namespace basic {
     //% help=basic/clear-screen weight=79
     //% blockId=device_clear_display block="clear screen"
     //% parts="ledmatrix"
+    //% advanced=true
     void clearScreen() {
       uBit.display.image.clear();
     }