* minibuffer.el (minibuffer): Move group from cus-edit.el.

* minibuffer.el (minibuffer): Move group from cus-edit.el.
(completion-auto-help): Move from C code.
(minibuffer--maybe-completion-help): Remove.
(minibuffer--bitset): New function.
(minibuffer--do-completion): Rename from minibuffer-do-completion.
Renumber a bit.  Really complete on string *before* point.
Add argument used for word-completion.
Join trailing / in completion with following text, as done in
minibuffer-complete-word.
Handle new value `lazy' for completion-auto-help.
(minibuffer-try-word-completion): New function extracted from
minibuffer-complete-word.
(minibuffer-complete-word): Use minibuffer--do-completion.
(minibuffer--insert-strings): Rename from
minibuffer-complete-insert-strings.
(exit-minibuffer): Fix typo.
* cus-edit.el (minibuffer): Move group to minibuffer.el.
* cus-start.el: Remove completion-auto-help.
* minibuf.c (Vcompletion_auto_help): Move to minibuffer.el.
(syms_of_minibuf): Remove its initialization.