Add method unbindEvents to not destroy the display like with destroy

[kopax-polyconseil]

Hi, I am working on a flask jinja2 backoffice and we use your module, thank you for it.

We use turbo-from, this is a jinja2 module that perform XHR request, for this reason, we need to unbindEvent and rebindEvent often.

When unbinding event, we use select.destroy(), which literally revert the initialization done with TomSelect, including revert HTML change and event binding.

This cause our UI to flash every request, due to the reverted HTML change.

This feature request would add a select.unbindEvents() method, that doesn't touch html and only unbindEvents.