check directory existence in setting function
remq -> delq
new function `slideview-concat-prev-if-image'
remove trailing space
add setting function
testing
add new hooks when forward/backward file.
remove testing
bugfix use `save-window-excursion'
ver up
a bit clean up code
fix respect `mode-class' if special.
new hook `slideview-move-file-hook'
remove trailing space