Bugfix. Latest version just allowed you to enter the editor once

btw, is there something wrong with the framebuffoer or did I create another error?
crash.log always contains after exit:

./luajit: ffi/framebuffer_linux.lua:284: missing declaration for symbol 'munmap'
stack traceback:
	[C]: in function '__index'
	ffi/framebuffer_linux.lua:284: in function 'close'
	frontend/ui/device/screen.lua:244: in function 'close'
	./reader.lua:66: in function 'exitReader'
	./reader.lua:215: in main chunk
	[C]: in function 'dofile'
	./koreader-base:22: in main chunk
	[C]: at 0x0000bd85