Add interface definition for platform-specific storage of configuration data; Modify NxWM unit test to use these interfaces, if available, to save and restore touchscreen calibration data.

Telnetd:  Missing argument in debug statement can cause crash in certain error conditions.  From David Sidrane

New touchscreen scaling algorithm for the case where measured X values vary with y position (and vice versa)

NxWM::CCalibration: Add logic to collect and average samples, optionally discarding the most extreem values

Misc changes to README files; Update SAMA5D3x-EK NxWM configuration to use Calibration instruction messages

NxWM::CCalibration:  Add an option to provide some instructions in the center of the calibration screen

apps/system/sysinfo:  Ken Petit reportst that the sysinfo command's stack size is marginal.  Stack size is now configurable with a default of 1024 bytes

apps/Makefile should include external/Make.defs so that external applications can participate in the menu configuration

Another case where we should use the routing table: There may be multiple routers on the same network.  In that case, we have to search for the routing table for the router that forwards to the destination address.  We do this when we determine the MAC address we want in the ARP logic

More improvements to the minimal NSH when there is no file system and when print fieldwidths are suppressed