delete some code related to PsychImaging

Author: marcobarilari

initPTB.m

@@ -63,10 +63,6 @@
 
 cfg.screen = max(Screen('Screens')); % Main screen
 
-% Open a fullscreen, onscreen window with gray background. Enable 32bpc
-% floating point framebuffer via imaging pipeline on it.
-PsychImaging('PrepareConfiguration');
-
 % init PTB with different options in concordance to the Debug Parameters
 if cfg.debug