UI scaling changes

A quick update. The UI should scale correctly on all resolutions, including 4K, and the default should look the same as it does on my own monitor's paltry FHD resolution. You may have to visit the UI Scaling option (Options > Graphics and Sound > UI Scaling) first for all of this to take effect.

Also, some bugfixes and under-the-hood optimizations.

But let me know if anything broke.

Happy tiring!