Option to not dim wallpaper

[highfiverobot]

Hey, great app.

I have a request to add an option to not dim the wallpaper on AcDisplay.

I purposefully choose wallpapers that don't conflict with the white display text and would love for AcDisplay to respect that.

It creates a bit of a jarring display when you go from lockscreen to homescreen, and I would love a more unified display.

Thanks, devs!