Add a "Stretched Texture" mode for Zoom Overlay

[EnnuiL]

Huh????? The old "Use Spyglass Overlay" tweak looked surprisingly good???
The vignette has been completely changed to act like Minecraft's vignette, which means it doesn't work for a textured (and stretched) overlay anymore; Let's fix that and reintroduce overlays in that stretched glory!

PS: The way the spyglass texture is applied should probably be revisited, or I should create a whole "Overlay" section

[EnnuiL]

I almost added it as part of The Checkpoint Update, but I didn't want to add new untranslated text just yet, so it might truly be a new feature for The Rebirth Update: Part 3. That will let me bring a polished version of it anyway