Add code from gpsim and disimrank toolboxes. Update copyright notice in LICENSE.txt and add AUTHORS.txt.
Add code from gpsim and disimrank toolboxes.
Update copyright notice in LICENSE.txt and add AUTHORS.txt.

SheffieldML/GPmat,SheffieldML/GPmat,TianpeiLuke/GPmat,TianpeiLuke/GPmat,SheffieldML/GPmat,TianpeiLuke/GPmat,TianpeiLuke/GPmat,SheffieldML/GPmat,SheffieldML/GPmat,TianpeiLuke/GPmat,TianpeiLuke/GPmat,SheffieldML/GPmat