Start the decoupling of ace-window and avy-jump
The dependencies now are ace-window -> avy-jump -> avy.
* ace-window.el (aw-overlays-lead): Rename to `avy--overlays-lead'.
(aw--done): Update.
(aw--remove-leading-chars): Rename to `aw--remove-leading-chars'.
(aw-select): Update.
* avy-init.el: Move requires after byte compiling.
* avy-jump.el (ace-window): Remove require.
(avy-background-face): New
defface.
(avi--process): Update.
(avy--overlays-back): New defvar.
(avy--make-backgrounds): New defun.
(avy--done): New defun.
(avy--overlays-lead): Rename from `aw-overlays-lead'.
(avy--remove-leading-chars): Rename from `aw--remove-leading-chars'.
(avi--overlay): Update.
(avi--overlay-at): Update.