partially revert
r1fba650c2aa4 on misc/physfs/CMakeLists.txt which randomly set true and false variables
hides the 'email' prompt on the feedback page (as that doesn't work, so it's a misleading/useless feature), makes the "please add your email" text a little nicer and more noticeable, and makes the "feedback" and "downloadable content" buttons on the main menu a little bit larger, and more clickable.