(a) split lazy-lock-defer-time into lazy-lock-defer-time and lazy-lock-defer-on-the...

(a) split lazy-lock-defer-time into lazy-lock-defer-time and lazy-lock-defer-on-the-fly, (b) add lazy-lock-defer-on-scrolling, (c) use these to choose one of lazy-lock-defer-line-after-change, lazy-lock-defer-rest-after-change, lazy-lock-fontify-line-after-change, lazy-lock-fontify-rest-after-change to add to after-change-functions, (d) use with-current-buffer rather than save-excursion, (e) avoid integer overflow in lazy-lock-percent-fontified.