Add ability to change on-hover delay for image tooltips

[KLE-France]

The "Tooltips" function for images in the browser (Tools > Settings... > Browser > Tooltip) is very useful, permitting an access to specific information on the image without the space-consuming "Thumbnails + labels" view.

However the built-in on-hover delay* is, at least in my opinion, too short. The slightest micro-pause when moving the mouse around in the browser's thumbnail window provokes a "flash" of the tooltip. This is very harsh and jarring visually speaking.

So, I would propose providing the user with the ability to modify the on-hover delay, with perhaps a default setting of 1 second (but modifiable in milliseconds).

As always, thanks for your consideration!

* Currently, the image-attached tooltips surely share the on-hover delay of the toolbar tooltips. Ideally, it would be good to separate those, but I don't think it would be a big deal if they can't be separated.