Add "sharp-linear" scaling option

[anpage]

This adds a special "sharp-linear" option to the Scaler ini setting which uses a render target texture to do an integer scale up to some resolution higher than the viewport before a final linear scale back down. This produces a sharp image that doesn't exhibit weird thick lines in text or other uneven pixels.

It's a little computationally heavy to be scaling up so high, but on machines with plenty of headroom, the boost in image quality is probably worth it.

Nearest

"sharp-linear"

[hifi]

Does this currently work correctly when toggling fullscreen with the alt-enter? Don't those integer calculations get called only once regardless of being in the fullscreen or windowed initially?

[anpage]

Does this currently work correctly when toggling fullscreen with the alt-enter? Don't those integer calculations get called only once regardless of being in the fullscreen or windowed initially?

Good catch. I changed it to re-init the render target texture whenever fullscreen is toggled.

[OmniBlade]

Just a note that this will address #512 by the looks of it.

[anpage]

I've rebased this (admittedly aging) PR and made the requested changes to string comparisons.