Changed to CoreNG
Implemented chrishamm's latest Network and Webserver changes, including
Telnet streaming
Added S parameter to M997 command for DuetNG
Increased file read block size to 2K when getting file info
Merged in chrishamm's changes to Network, PrintMonitor, and his support
for firmware updates from SD card
Fixed print monitor issue that threw out the layer count and time
estimates when there was an initial extruder priming move in the start
gcode