update copyright

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man/feh.pre

src/debug.h

src/events.c

src/feh.h

src/filelist.c

src/help.raw

src/imlib.c

src/index.c

src/keyevents.c

src/list.c

src/main.c

src/menu.c

src/menu.h

src/options.c

src/options.h

src/signals.c

src/slideshow.c

src/structs.h

src/thumbnail.c