Various fixes from initial attempts to integrate the SAMA5 SSC/I2C driver with the I2C character driver loopback test

NxPlayer play thread stack size is now configurable;  all NxPlayer threads are named via pthread_setname_np().  From Ken Pettit

Correct unitialization of composite USB device.  A stale pointer was being reused.  From David Sidrane

Extend stack debug logic to include IDLE and interrupt stacks.  Also color the heap as well.  Based on suggestions from David Sidrane

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)