fix bug with maxLesson, last and next button work again
fix bug with maxLesson, last and next button work again

antonleykin/InteractiveShell,fhinkel/tryM2,fhinkel/InteractiveShell,fhinkel/tryM2,antonleykin/InteractiveShell,fhinkel/tryM2,antonleykin/InteractiveShell,fhinkel/InteractiveShell,fhinkel/InteractiveShell,YueRen/tryM2,fhinkel/InteractiveShell,YueRen/tryM2,fhinkel/tryM2,YueRen/tryM2