add eyegaze libraries
add eyegaze control structures
attribute to distinguish different eyetrackers
setter and getter for eyetracker type
distinguish initializations of different ET
remove leavings
initialize only one time
handle eyegaze ET initialization
handle different calibrations
distinguish different starts
the filename should be the same for every ET
eyegaze ET start method
distinguish different stops
eyegaze ET stop method
and last but not least, the trigger handling