init.el: Modify set-tab-width
init.el: Refactor setting of windows
init.el: Refactor setting of ibuffer
init.el: Refactor setting of dired
init.el: Modify diff-switches
init.el: Refactor setting of diff-mode
init.el: Add ediff-diff-options variable
init.el: Refactor setting of ediff
init.el: Refactor setting of magit