* mwheel.el (mwheel-installed-bindings): New var.

* mwheel.el (mwheel-installed-bindings): New var.
(mouse-wheel-mode): Use it, so as to make sure we really remove all
the bindings we set last time.  Use custom-initialize-delay.
* loadup.el: Load mwheel after term/*-win.el.
* startup.el (command-line): Don't reevaluate mouse-wheel-down-event
and mouse-wheel-up-event now that their first evaluation is done
sufficiently late to be correct.