init.el: Remove popwin:add-special-display-config and code using it
init.el: Support magit in popwin
init.el: Remove ibuffer-add-maybe-show-predicates and code using it
init.el: Modify ibuffer-maybe-show-predicates
init.el: Add safe-define-key function
init.el: Add global-safe-set-key function
init.el: Modify define-keys
init.el: Refactor code using safe-define-key