Test core_update function and SimplePie fix

By dobrado on 19 July 2019, 1:12pm
The previous core update to IDNA Convert class means npdata.ser file is no longer required, so try using core_update to remove it. Also fixed another SimplePie bug in Misc.php due to NULL empty string mismatch.
core 4 0
< New version of IDNA Convert classReader >