Calibration for the Touch Screen

The touch screen driver (../drivers/touch.c) has default parameters,
represented by the array g_pi32TouchParameters, to align the touch screen's
cooordinates to the display coordinates.  But these parameters might need
calibration to achieve a better alignment, of the touch and display
coordiantes.

The raw sample interface of the touch screen driver is used to compute the
calibration matrix required to convert raw samples into screen X/Y
positions.  The produced calibration matrix can be inserted into the touch
screen driver to map the raw samples into screen coordinates.

The touch screen calibration is performed according to the algorithm
described by Carlos E. Videles in the June 2002 issue of Embedded Systems
Design.  It can be found online at
<a href="http://www.embedded.com/story/OEG20020529S0046">
http://www.embedded.com/story/OEG20020529S0046</a>.

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This is part of revision 2.1.4.178 of the DK-TM4C129X Firmware Package.
